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Journal articles on the topic 'OpenFOAM Methodology'
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1
Segui, M., F. R. Abel, R. M. Botez, and A. Ceruti. "High-fidelity aerodynamic modeling of an aircraft using OpenFoam – application on the CRJ700." Aeronautical Journal 126, no. 1298 (October 7, 2021): 585–606. http://dx.doi.org/10.1017/aer.2021.86.
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AbstractThis study is focused on the development of longitudinal aerodynamic models for steady flight conditions. While several commercial solvers are available for this type of work, we seek to evaluate the accuracy of an open source software. This study aims to verify and demonstrate the accuracy of the OpenFoam solver when it is used on basic computers (32–64GB of RAM and eight cores). A new methodology was developed to show how an aerodynamic model of an aircraft could be designed using OpenFoam software. The mesh and the simulations were designed only using OpenFoam utilities, such as blockMesh, snappyHexMesh, simpleFoam and rhoSimpleFoam. For the methodology illustration, the process was applied to the Bombardier CRJ700 aircraft and simulations were performed for its flight envelope, up to M0.79. Forces and moments obtained with the OpenFoam model were compared with an accurate flight data source (level D flight simulator). Excellent results in data agreement were obtained with a maximum absolute error of 0.0026 for the drag coefficient, thus validating a high-fidelity aerodynamic model for the Bombardier CRJ-700 aircraft.
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RODRIGUEZ LUZARDO, SIMON ANTONIO, and Philip Cardiff. "A General Approach for Running Python Codes in OpenFOAM Using an Embedded PYBIND11 Python Interpreter." OpenFOAM® Journal 2 (December 15, 2022): 166–82. http://dx.doi.org/10.51560/ofj.v2.79.
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As the overlap between traditional computational mechanics and machine learning grows, there is an increasing demand for straight-forward approaches to interface Python-based procedures with C++-based OpenFOAM. This article introduces one such general methodology, allowing the execution of Python code directly within an OpenFOAM solver without the need for Python code translation. The proposed approach is based on the lightweight library pybind11, where OpenFOAM data is transferred to an embedded Python interpreter for manipulation, and results are returned as needed. Following a review of related approaches, the article describes the approach, with a particular focus on data transfer between Python and OpenFOAM, executing Python scripts and functions, and practical details about the implementation in OpenFOAM. Three complementary test cases are presented to highlight the functionality and demonstrate the effect of different data transfer approaches: a Python-based velocity profile boundary condition; a Python-based solver for prototyping; and a machine learning mechanical constitutive law class for solids4foam which performs field calculations.
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Venier, Cesar Martin, Andrés Reyes Urrutia, Juan Pablo Capossio, Jan Baeyens, and Germán Mazza. "Comparing ANSYS Fluent® and OpenFOAM® simulations of Geldart A, B and D bubbling fluidized bed hydrodynamics." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 1 (September 12, 2019): 93–118. http://dx.doi.org/10.1108/hff-04-2019-0298.
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Purpose The purpose of this study is to assess the performance of ANSYS Fluent® and OpenFOAM®, at their current state of development, to study the relevant bubbling fluidized bed (BFB) characteristics with Geldart A, B and D particles. Design/methodology/approach For typical Geldart B and D particles, both a three-dimensional cylindrical and a pseudo-two-dimensional arrangement were used to measure the bed pressure drop and solids volume fraction, the latter by digital image analysis techniques. For a typical Geldart A particle, specifically to examine bubbling and slugging phenomena, a 2 m high three-dimensional cylindrical arrangement of small internal diameter was used. The hydrodynamics of the experimentally investigated BFB cases were also simulated for identical geometries and operating conditions using OpenFOAM® v6.0 and ANSYS Fluent® v19.2 at identical mesh and numerical setups. Findings The comparison between experimental and simulated results showed that both ANSYS Fluent® and OpenFOAM® provide a fair qualitative prediction of the bubble sizes and solids fraction for freely-bubbling Geldart B and D particles. For Geldart A particles, operated in a slugging mode, the qualitative predictions are again quite fair, but numerical values of relevant slug characteristics (length, velocity and frequency) slightly favor the use of OpenFOAM®, despite some deviations of predicted slug velocities. Originality/value A useful comparison of computational fluid dynamics (CFD) software performance for different fluidized regimes is presented. The results are discussed and recommendations are formulated for the selection of the CFD software and models involved.
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Lavesson, Nils, Jonathan Jogenfors, and Ola Widlund. "Modeling of streamers in transformer oil using OpenFOAM." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 33, no. 4 (July 1, 2014): 1272–81. http://dx.doi.org/10.1108/compel-12-2012-0361.
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Purpose – A model for streamers based on charge transport has been developed by MIT and ABB. The purpose of this paper is to investigate the consequences of changing numerical method from the finite element method (FEM) to the finite volume method (FVM) for simulations using the streamer model. The new solver is also used to extend the simulations to 3D. Design/methodology/approach – The equations from the MIT-ABB streamer model are implemented in OpenFOAM which uses the FVM. Checks of the results are performed including verification of convergence. The solver is then applied to some of the key simulations from the FEM model and results presented. Findings – The results for second mode streamers are confirmed, whereas the results for third mode streamers differ significantly leading to questioning of one hypothesis proposed based on the FEM results. The 3D simulations give consistent results and show a way forward for future simulations. Originality/value – The FVM has not been applied to the model before and led to more confidence in second mode result and revising of third mode results. In addition the new simulation method makes it possible to extend the results to 3D.
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Kamliya Jawahar, Hasan, Yujing Lin, and Mark Savill. "Large eddy simulation of airfoil self-noise using OpenFOAM." Aircraft Engineering and Aerospace Technology 90, no. 1 (January 2, 2018): 126–33. http://dx.doi.org/10.1108/aeat-05-2015-0130.
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Purpose The purpose of this paper is to investigate airfoil self-noise generation and propagation by using a hybrid method based on the large-eddy simulation (LES) approach and Curle’s acoustic analogy as implemented in OpenFOAM. Design/methodology/approach Large-eddy simulation of near-field flow over a NACA6512-63 airfoil at zero angle of attack with a boundary layer trip at Rec = 1.9 × 105 has been carried out using the OpenFOAM® computational fluid dynamics (CFD) code. Calculated flow results are compared with published experimental data. The LES includes the wind tunnel installation effects by using appropriate inflow boundary conditions obtained from a RANS κ – ω SST model computation of the whole wind tunnel domain. Far-field noise prediction was achieved by an integral method based on Curle’s acoustic analogy. The predicted sound pressure levels are validated against the experimental data at various frequency ranges. Findings The numerical results presented in this paper show that the flow features around a NACA6512-63 airfoil have been correctly captured in OpenFOAM LES calculations. The mean surface pressure distributions and the local pressure peaks for the step trip setup agree very well with the experimental measurements. Aeroacoustic prediction using Curle’s analogy shows an overall agreement with the experimental data. The sound pressure level-frequency spectral analysis produces very similar data at low to medium frequency, whereas the experimentally observed levels are slightly over predicted at a higher frequency range. Practical implications This study has achieved and evaluated an alternative aeroacoustic simulation method based on the combination of LES with a simple Smagorinsky SGS model and Curle’s analogy, as implemented in the OpenFOAM CFD code. The unsteady velocity/pressure source data produced can be used for any simpler analytically based far-field noise prediction scheme. Originality/value A complete integration of the LES and Curle’s acoustic analogy for aeroacoustic simulations has been achieved in OpenFOAM. The capability and accuracy of the hybrid method are fully evaluated for high-camber airfoil self-noise predictions. Wind tunnel installation effects have been incorporated properly into the LES.
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Masoomi, Mobin, Mahdi Yousefifard, and Amir Mosavi. "Efficiency Assessment of an Amended Oscillating Water Column Using OpenFOAM." Sustainability 13, no. 10 (May 18, 2021): 5633. http://dx.doi.org/10.3390/su13105633.
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Oscillating water column (OWC) is an advanced form of wave energy converter (WEC). This study aims at improving the efficiency of an amended OWC through a novel methodology for simulating several vertical plates within the chamber. This paper provides a numerical investigation considering one, two, three, and four vertical plates. The open field operation and manipulation (OpenFOAM) solver is verified based on the Reynolds-Averaged Navier–Stokes (RANS) equation. Results show the number and the position of plates where the convertor’s efficiency improves. The work undertaken here also revealed a reduction in the net force imposed on the convertor’s structure, especially the front wall. Consequently, adding plates acquires more efficiency with lower force on the system.
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Plua, Frank A., Francisco-Javier Sánchez-Romero, Victor Hidalgo, Petra Amparo López-Jiménez, and Modesto Pérez-Sánchez. "Variable Speed Control in PATs: Theoretical, Experimental and Numerical Modelling." Water 15, no. 10 (May 19, 2023): 1928. http://dx.doi.org/10.3390/w15101928.
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The selection of pumps as turbines (PATs) for their respective use in energy optimisation systems is a complicated task, because manufacturers do not provide the characteristic curves. For this reason, some research has been carried out to predict them with computational fluid dynamics (CFD) and mathematical models. The purpose of this study is to validate these two prediction methodologies of flow (Q) vs. head (H) curves through numerical modelling using the computational package OpenFOAM, together with a comparison with the experimental data obtained from a PAT for the case in which the nominal rotation speed of the machine varies. Depending on the configuration and working conditions of the PAT, the simulation performed with OpenFOAM was validated by calibrating it with the nominal curve of the pump and with another simulation performed with CFD workbench SOLIDWORKS FloEFD. Subsequently, the second methodology related to the analyses and mathematical models proposed to predict the Q vs. H curves were also validated with new models in OpenFOAM and the experimental data. The results show that these prediction methods are effective when a machine’s operating point is close to the BEP (best efficient point). The absolute error ranges obtained with these two prediction methodologies for rotation speeds of 880 rpm, 1020 rpm, 1200 rpm, and 1500 rpm are between 5 and 24%, 2 and 17%, 0 and 12%, and 1 and 24%, respectively.
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St-Onge, Gabriel, and Mathieu Olivier. "Modular Framework for the Solution of Boundary-coupled Multiphysics Problems." OpenFOAM® Journal 3 (July 31, 2023): 120–45. http://dx.doi.org/10.51560/ofj.v3.64.
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This paper presents a modular multiphysics framework developed for OpenFOAM. The framework is built around an iterative implicit coupling scheme based on a multi-region partitioned approach. This scheme allows the implementation of formal implicit time-marching schemes, which improves the stability of strongly interacting coupled problems. This methodology allows physical interactions to be handled through specifically designed interface boundary conditions. It also allows region-specific solvers to be implemented as modular class solvers. The coupling methodology is handled with a main program that manages solver-specific actions. The aim of this framework is to facilitate the implementation and testing of new multiphysics coupling problems in an integrated code structure. To show the capabilities of the framework to integrate new physics, solvers and boundary conditions requirements are discussed. Also, three validated examples involving fluid-structure interactions, conjugate heat transfer, and fluid-structure-thermal interactions are presented. Although all these problems are boundary-coupled multiphysics problems, the framework is conceptually not limited to this kind of problems. The benefit of this work to the OpenFOAM community is a general and modular framework that facilitates the setup and solution of diversified multiphysics problems, and that illustrates the implementation of modular interface boundary conditions between physics regions.
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Saroha, Sagar, Sawan S. Sinha, and Sunil Lakshmipathy. "Evaluation of PANS method in conjunction with non-linear eddy viscosity closure using OpenFOAM." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 3 (March 4, 2019): 949–80. http://dx.doi.org/10.1108/hff-09-2018-0529.
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Purpose In recent years, the partially averaged Navier–Stokes (PANS) methodology has earned acceptability as a viable scale-resolving bridging method of turbulence. To further enhance its capabilities, especially for simulating separated flows past bluff bodies, this paper aims to combine PANS with a non-linear eddy viscosity model (NLEVM). Design/methodology/approach The authors first extract a PANS closure model using the Shih’s quadratic eddy viscosity closure model [originally proposed for Reynolds-averaged Navier–Stokes (RANS) paradigm (Shih et al., 1993)]. Subsequently, they perform an extensive evaluation of the combination (PANS + NLEVM). Findings The NLEVM + PANS combination shows promising result in terms of reduction of the anisotropy tensor when the filter parameter (fk) is reduced. Further, the influence of PANS filter parameter f on the magnitude and orientation of the non-linear part of the stress tensor is closely scrutinized. Evaluation of the NLEVM + PANS combination is subsequently performed for flow past a square cylinder at Reynolds number of 22,000. The results show that for the same level of reduction in fk, the PANS + NLEVM methodology releases significantly more scales of motion and unsteadiness as compared to the traditional linear eddy viscosity model (LEVM) of Boussinesq (PANS + LEVM). The authors further demonstrate that with this enhanced ability the NLEVM + PANS combination shows much-improved predictions of almost all the mean quantities compared to those observed in simulations using LEVM + PANS. Research limitations/implications Based on these results, the authors propose the NLEVM + PANS combination as a more potent methodology for reliable prediction of highly separated flow fields. Originality/value Combination of a quadratic eddy viscosity closure model with PANS framework for simulating flow past bluff bodies.
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Cremades Rey, Luis F., Denis F. Hinz, and Mahdi Abkar. "Reynolds Stress Perturbation for Epistemic Uncertainty Quantification of RANS Models Implemented in OpenFOAM." Fluids 4, no. 2 (June 22, 2019): 113. http://dx.doi.org/10.3390/fluids4020113.
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Reynolds-averaged Navier-Stokes (RANS) models are widely used for the simulation of engineering problems. The turbulent-viscosity hypothesis is a central assumption to achieve closures in this class of models. This assumption introduces structural or so-called epistemic uncertainty. Estimating that epistemic uncertainty is a promising approach towards improving the reliability of RANS simulations. In this study, we adopt a methodology to estimate the epistemic uncertainty by perturbing the Reynolds stress tensor. We focus on the perturbation of the turbulent kinetic energy and the eigenvalues separately. We first implement this methodology in the open source package OpenFOAM. Then, we apply this framework to the backward-facing step benchmark case and compare the results with the unperturbed RANS model, available direct numerical simulation data and available experimental data. It is shown that the perturbation of both parameters successfully estimate the region bounding the most accurate results.
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Schmitt, Pál, Christian Windt, Josh Davidson, John V. Ringwood, and Trevor Whittaker. "Beyond VoF: alternative OpenFOAM solvers for numerical wave tanks." Journal of Ocean Engineering and Marine Energy 6, no. 3 (August 2020): 277–92. http://dx.doi.org/10.1007/s40722-020-00173-9.
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Abstract The vast majority of numerical wave tank applications are solved using finite volume-based, volume of fluid methods. One popular numerical modelling framework is OpenFOAM and its two phase solvers, interFoam and interIsoFoam, enabling the simulation of a broad range of marine hydrodynamic phenomena. However, in many applications, certain aspects of the entire set of possible hydrodynamic phenomena are not of interest and the reduced complexity could allow the use of simpler, more computationally efficient solvers. One barrier for the application of such alternative solvers is the lack of suitable wavemaking and absorption capabilities, which this paper aims to address. A wavemaking and absorption methodology is presented, which can be applied to different solvers using the same fundamental concept. The implementation is presented for interFoam and interIsoFoam, as well as two other solvers whose use as numerical wave tanks has not previously been reported in the literature, shallowWaterFoam and potentialFreeSurfaceFoam. Parameter studies are performed to guide the user in the use of the methods. Example applications for two industrially relevant test cases are demonstrated; a multi-frequency wave packet focused at one position over flat bottom and regular waves propagating over a submerged shoal. All solvers yielded useful results, but some complex wave transformations in the shoal case were only resolved by the VoF methods. Alternative methods beyond the already well established VoF methods seem worth considering because potential for significant reductions in computational effort exist.
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Mavi, Anele, and Tiri Chinyoka. "Finite Volume Computational Analysis of the Heat Transfer Characteristic in a Double-Cylinder Counter-Flow Heat Exchanger with Viscoelastic Fluids." Defect and Diffusion Forum 424 (May 8, 2023): 19–43. http://dx.doi.org/10.4028/p-j482zy.
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This work presents a computational analysis of the heat-exchange characteristics in a double-cylinder (also known as a double-pipe) geometrical arrangement. The heat-exchange is from a hotter viscoelastic fluid flowing in the core (inner) cylinder to a cooler Newtonian fluid flowing in the shell (outer) annulus. For optimal heat-exchange characteristics, the core and shell fluid flow in opposite directions, the so-called counter-flow arrangement.The mathematical modelling of the given problem reduces to a system of nonlinear coupled Partial Differential Equations (PDEs). Specifically, the rheological behaviour of the core fluid is governed by the Giesekus viscoelastic constitutive model. The governing system of coupled nonlinear PDEs is intractable to analytic treatment and hence is solved numerically using Finite Volume Methods (FVM). The FVM numerical methodology is implemented via the open-source software package OpenFOAM. The numerical methods are stabilized, specifically to address numerical instabilities arising from the High Weissenberg Number Problem (HWNP), via a combination of the Discrete Elastic Viscous Stress Splitting (DEVSS) technique and the Log-Conformation Reformulation (LCR) methodology. The DEVSS and LCR stabilization techniques are integrated into the relevant viscoelastic fluid solvers. The novelties of the study center around the simulation and analysis of the optimal heat-exchange characteristics between the heated Giesekus fluid and the coolant Newtonian fluid within a double-pipe counter-flow arrangement. Existing studies in the literature have either focused exclusively on Newtonian fluids and/or on rectangular geometries. The existing OpenFOAM solvers have also largely focused on non-isothermal viscoelastic flows. The relevant OpenFOAM solvers are modified for the present purposes by incorporating the energy equation for viscoelastic fluid flow. The flow characteristics are presented qualitatively (graphically) via the fluid pressure, temperature, velocity, and the polymer-stress components as well as the related normal stress differences. The results illustrate the required decrease in the core fluid temperature in the longitudinal direction due to the cooling effects of the shell fluid, whose temperature predictably increases in the counter-flow direction.
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Espinel, Edwin, Guillermo Valencia, and Jorge Duarte Forero. "CFD Methodology for the Optimization of a Centrifugal Fan with Backward Inclined Blades Using OpenFOAM®." International Journal on Energy Conversion (IRECON) 8, no. 3 (May 31, 2020): 80. http://dx.doi.org/10.15866/irecon.v8i3.18641.
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Zhang, Yuxiang, Reamonn MacReamoinn, Philip Cardiff, and Jennifer Keenahan. "Analyzing Wind Effects on Long-Span Bridges: A Viable Numerical Modelling Methodology Using OpenFOAM for Industrial Applications." Infrastructures 8, no. 9 (August 26, 2023): 130. http://dx.doi.org/10.3390/infrastructures8090130.
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Aerodynamic performance is of critical importance to the design of long-span bridges. Computational fluid dynamics (CFD) modelling offers bridge designers an opportunity to investigate aerodynamic performance for long-span bridges during the design phase as well as during operation of the bridge. It offers distinct advantages when compared with the current standard practice of wind tunnel testing, which can have several limitations. The proposed revisions to the Eurocodes offer CFD as a methodology for wind analysis of bridges. Practicing engineers have long sought a computationally affordable, viable, and robust framework for industrial applications of using CFD to examine wind effects on long-span bridges. To address this gap in the literature and guidance, this paper explicitly presents a framework and demonstrates a workflow of analyzing wind effects on long-span bridges using open-source software, namely FreeCAD, OpenFOAM, and ParaView. Example cases are presented, and detailed configurations and general guidance are discussed during each step. A summary is provided of the validation of this methodology with field data collected from the structural health monitoring (SHM) systems of two long-span bridges.
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Peña-Monferrer, Carlos, and Carmen Diaz-Marin. "rom.js/cfd.xyz: An open-source framework for generating and visualizing parametric CFD results." OpenFOAM® Journal 2 (October 10, 2022): 143–48. http://dx.doi.org/10.51560/ofj.v2.83.
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We present in this technical note an open-source web framework for the generation and visualization of parametric OpenFOAM simulations from surrogate models. It consists of a JavaScript module (rom.js) and a web app (cfd.xyz) to explore fluid dynamics problems efficiently and easily for a wide range of parameters. rom.js is a JavaScript port of a set of open-source packages (Eigen, Splinter, VTK/C++ and ITHACA-FV) to solve the online stage of reduced-order models (ROM) generated by the ITHACA-FV tool. It can be executed outside a web browser within a backend JavaScript runtime environment, or in a given web solution. This methodology can also be extended to methods using machine learning. The rom.js module was used in cfd.xyz, an open-source web service to deliver a collection of interactive CFD cases in a parametric space. The framework includes some tutorials, showing the whole process from the generation of the surrogate model to the web browser. It also includes a standalone web tool for visualizing users' ROMs by directly dragging and dropping the output folder of the offline stage. Beyond the current proof of technology, this enables a collaborative effort for the implementation of OpenFOAM surrogate models in applications demanding real-time solutions such as digital twins and other digital transformation technologies.
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Borisov, Vitaly Evgenyevich, Victor Timofeevich Zhukov, Mikhail Mikhailovich Krasnov, Boris Viktorovich Kritskiy, Natalia Dmitrievna Novikova, Yuri Germanovich Rykov, and Olga Borisovna Feodoritova. "Program package NOISEtte-MCFL for simulation multicomponent reacting flows." Keldysh Institute Preprints, no. 6 (2023): 1–23. http://dx.doi.org/10.20948/prepr-2023-6.
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The research software package NOISEtte–MCFL is designed to simulate multicomponent gas dynamic flows taking into account conjugate heat transfer. The NOISEtte–MCFL code is based on the developed original mathematical methodology based on the splitting algorithm for physical processes and an explicit iterative scheme based on Chebyshev polynomials. NOISEtte–MCFL is written in C++ and uses a hybrid three-level parallel structure, including MPI, OpenMP and CUDA technologies. The package is validated and verified on a set of model problems and standard test cases. Comparison with the results of calculations using the commercial ANSYS code and the open source OpenFOAM software is performed.
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Castaño, Santiago López, Andrea Petronio, and Giovanni Petris and Vincenzo Armenio . "Assessment of Solution Algorithms for LES of Turbulent Flows Using OpenFOAM." Fluids 4, no. 3 (September 12, 2019): 171. http://dx.doi.org/10.3390/fluids4030171.
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We validate and test two algorithms for the time integration of the Boussinesq form of the Navier—Stokes equations within the Large Eddy Simulation (LES) methodology for turbulent flows. The algorithms are implemented in the OpenFOAM framework. From one side, we have implemented an energy-conserving incremental-pressure Runge–Kutta (RK4) projection method for the solution of the Navier–Stokes equations together with a dynamic Lagrangian mixed model for momentum and scalar subgrid-scale (SGS) fluxes; from the other side we revisit the PISO algorithm present in OpenFOAM (pisoFoam) in conjunction with the dynamic eddy-viscosity model for SGS momentum fluxes and a Reynolds Analogy for the scalar SGS fluxes, and used for the study of turbulent channel flows and buoyancy-driven flows. In both cases the validity of the anisotropic filter function, suited for non-homogeneous hexahedral meshes, has been studied and proven to be useful for industrial LES. Preliminary tests on energy-conservation properties of the algorithms studied (without the inclusion of the subgrid-scale models) show the superiority of RK4 over pisoFoam, which exhibits dissipative features. We carried out additional tests for wall-bounded channel flow and for Rayleigh–Bènard convection in the turbulent regime, by running LES using both algorithms. Results show the RK4 algorithm together with the dynamic Lagrangian mixed model gives better results in the cases analyzed for both first- and second-order statistics. On the other hand, the dissipative features of pisoFoam detected in the previous tests reflect in a less accurate evaluation of the statistics of the turbulent field, although the presence of the subgrid-scale model improves the quality of the results compared to a correspondent coarse direct numerical simulation. In case of Rayleigh–Bénard convection, the results of pisoFoam improve with increasing values of Rayleigh number, and this may be attributed to the Reynolds Analogy used for the subgrid-scale temperature fluxes. Finally, we point out that the present analysis holds for hexahedral meshes. More research is need for extension of the methods proposed to general unstructured grids.
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Suponitsky, Victoria, Ivan V. Khalzov, and Eldad J. Avital. "Magnetohydrodynamics Solver for a Two-Phase Free Surface Flow Developed in OpenFOAM." Fluids 7, no. 7 (June 21, 2022): 210. http://dx.doi.org/10.3390/fluids7070210.
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A magnetohydrodynamics solver (“mhdCompressibleInterFoam”) has been developed for a compressible two-phase flow with a free surface by extending “compressibleInterFoam” solver within OpenFOAM suite. The primary goal is to develop a tool to simulate compression of magnetic fields in vacuum and simplified magnetized plasma targets by imploding rotating liquid metal liners in the context of a Magnetized Target Fusion (MTF) concept in pursuit by General Fusion Inc. At present, the solver is limited to axisymmetric problems and the magnetic field evolution is solved in terms of toroidal field component and poloidal flux functions. The solver has been validated and verified using a number of test cases for which analytical or other numerical solutions are provided. Those tests cases include: (i) compression of toroidal and poloidal magnetic fields in vacuum and cylindrical geometry, (ii) axisymmetric annular Hartmann flow, and (iii) compression of magnetized target initialized with a Grad–Shafranov equilibrium state in a cylindrical geometry. A methodology to incorporate conductive solid regions into simulation has also been developed. Capability of the code is demonstrated by simulating a complex case of compressing a magnetized target, which is injected during implosion of a rotating liquid metal liner with an initially soaked poloidal magnetic field. An application of the solver to simulate compression of a magnetized target in a geometry and parameters relevant to the Fusion Demonstration Plant (FDP) being developed by General Fusion Inc. is also demonstrated.
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García-Camprubí, María, Carmen Alfaro-Isac, Belén Hernández-Gascón, José Ramón Valdés, and Salvador Izquierdo. "Numerical Approach for the Assessment of Micro-Textured Walls Effects on Rubber Injection Moulding." Polymers 13, no. 11 (May 26, 2021): 1739. http://dx.doi.org/10.3390/polym13111739.
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Micro-surface texturing of elastomeric seals is a validated method to improve the friction and wear characteristics of the seals. In this study, the injection process of high-viscosity elastomeric materials in moulds with wall microprotusions is evaluated. To this end, a novel CFD methodology is developed and implemented in OpenFOAM to address rubber flow behaviour at both microscale and macroscale. The first approach allows analyzing the flow perturbation induced by a particular surface texture and generate results to calculate an equivalent wall shear stress that is introduced into the macroscale case through reduced order modelling. The methodology is applied to simulate rubber injection in textured moulds in an academic case (straight pipe) and a real case (D-ring seal mould). In both cases, it is shown that textured walls do not increase the injection pressure and therefore the manufacturing process is not adversely affected.
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Sikirica, Ante, Luka Grbčić, Marta Alvir, and Lado Kranjčević. "Computational Efficiency Assessment of Adaptive Mesh Refinement for Turbulent Jets in Crossflow." Mathematics 10, no. 4 (February 17, 2022): 620. http://dx.doi.org/10.3390/math10040620.
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Numerical analyses of environmental discharges are commonly conducted on pre-generated numerical grids with refinements implemented in regions of interest or influence on the flow field. This approach to problem formulation relies on insights into the flow specifics so that appropriate attention is given to relevant segments of the domain. In this paper we investigated the applicability of adaptive mesh refinement (AMR) on a commonly considered environmental problem—a jet in crossflow. The assessment was made using the OpenFOAM toolbox. Several RANS turbulence models and grid generation approaches were compared in terms of accuracy to previous studies and experimental results. Main emphasis is given to the computational efficiency of the methodology with a focus on load distribution. Our findings indicate that the results are acceptable in terms of accuracy with load balancing providing significant computational savings thus enabling AMR methodology to outperform the conventional approach.
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Kang, Hyung-Seok, Sang-Min Kim, and Jongtae Kim. "Safety Issues of a Hydrogen Refueling Station and a Prediction for an Overpressure Reduction by a Barrier Using OpenFOAM Software for an SRI Explosion Test in an Open Space." Energies 15, no. 20 (October 13, 2022): 7556. http://dx.doi.org/10.3390/en15207556.
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Safety issues arising from a hydrogen explosion accident in Korea are discussed herein. In order to increase the safety of hydrogen refueling stations (HRSs), the Korea Gas Safety Corporation (KGS) decided to install a damage-mitigation wall, also referred to as a barrier, around the storage tanks at the HRSs after evaluating the consequences of hypothetical hydrogen explosion accidents based on the characteristics of each HRS. To propose a new regulation related to the barrier installation at the HRSs, which can ensure a proper separation distance between the HRS and its surrounding protected facilities in a complex city, KGS planned to test various barrier models under hypothetical hydrogen explosion accidents to develop a standard model of the barrier. A numerical simulation to investigate the effect of the recommended barrier during hypothetical hydrogen explosion accidents in the HRS will be performed before installing the barrier at the HRSs. A computational fluid dynamic (CFD) code based on the open-source software OpenFOAM will be developed for the numerical simulation of various accident scenarios. As the first step in the development of the CFD code, we conducted a hydrogen vapor cloud explosion test with a barrier in an open space, which was conducted by the Stanford Research Institute (SRI), using the modified XiFoam solver in OpenFOAM-v1912. A vapor cloud explosion (VCE) accident may occur due to the leakage of gaseous hydrogen or liquefied hydrogen owing to a failure of piping connected to the storage tank in an HRS. The analysis results using the modified XiFoam predicted the peak overpressure variation from the near field to the far field of the explosion site through the barrier with an error range of approximately ±30% if a proper analysis methodology including the proper mesh distribution in the grid model is chosen. In addition, we applied the proposed analysis methodology using the modified XiFoam to barrier shapes that varied from that used in the test to investigate its applicability to predict peak overpressure variations with various barrier shapes. Through the application analysis, we concluded that the proposed analysis methodology is sufficient for evaluating the safety effect of the barrier, which will be recommended through experimental research, during VCE accidents at the HRSs.
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Ivanov, Aleksandr Vladimirovich, Matvey Viktorovich Kraposhin, and Tatiana Gennadyevna Elizarova. "On a new method for regularizing equations two-phase incompressible fluid." Keldysh Institute Preprints, no. 61 (2021): 1–27. http://dx.doi.org/10.20948/prepr-2021-61.
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This paper presents a new method for the numerical simulation of two-phase incompressible immiscible flows. The methodology is based on the hydrodynamic equations regularization method using the quasi-hydrodynamic approach. Two systems of regularized equations are developed, which differ in terms of velocity regularization. The comparison of the described equations systems and the approbation of the numerical model on two numerical tests are given: dam break problem with the bottom step, for which the experimental data are described (Koshizuka’s experiment), and the cubic drop evolution problem. The latter problem is a model one with artificially specified parameters that demonstrates the effects of surface tension. A numerical model of two-phase flows is implemented in the open-source platform OpenFOAM using the finite volume method.
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Ghoudi, Zeineb, Souhail Maazioui, Fayssal Benkhaldoun, and Noureddine Hajjaji. "A New Rheological Model for Phosphate Slurry Flows." Fluids 8, no. 2 (February 8, 2023): 57. http://dx.doi.org/10.3390/fluids8020057.
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In this paper, a new rheological model for the flow of phosphate-water suspensions is proposed. The model’s ability to replicate the rheological characteristics of phosphate-water suspensions under different shear rate conditions is evaluated using rheometric tests, and it is found to be in good agreement with experimental data. A comprehensive methodology for obtaining the model parameters is presented. The proposed model is then incorporated into the OpenFoam numerical code. The results demonstrate that the model is capable of reproducing the rheological behavior of phosphate suspensions at both low and high concentrations by comparing it with suitable models for modeling the rheological behavior of phosphate suspensions. The proposed model can be applied to simulate and monitor phosphate slurry flows in industrial applications.
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Rajkumar, A., L. L. Ferrás, C. Fernandes, Olga S. Carneiro, and J. Miguel Nóbrega. "Guidelines for balancing the flow in extrusion dies: the influence of the material rheology." Journal of Polymer Engineering 38, no. 2 (February 23, 2018): 197–211. http://dx.doi.org/10.1515/polyeng-2016-0449.
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Abstract In this work we present improved design guidelines to support the die designer activity, when searching for the flow channel geometry that allows the achievement of a balanced flow distribution, in complex profile extrusion dies. The proposed methodology relies on surrogate models, obtained through a detailed and extensive numerical study, carried out with the open source computational library OpenFOAM®, in which an appropriate numerical solver for the problems under study was implemented. The main contribution of this work is to further enlarge the applicability of the simplified design methodology (Rajkumar A, Ferrás LL, Fernandes C, Carneiro OS, Becker M, Nóbrega JM. Int. Polym. Proc. 2017, 32, 58–71.) previously proposed by this group for similar purposes, by considering the effect of processing parameters and material rheology. The sensitivity analyses performed showed that, among the studied parameters, the power-law exponent was the only one that affected the system behavior. Thus, the previous proposed surrogate models were modified to include the effect of this parameter. Verification studies performed for three geometries and different rheological and process parameters evidenced the effectiveness of the proposed simplified design methodology.
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Cuevas-Vasquez, Delfina, Eduardo Sainz-Mejia, Javier Ortiz-Villafuerte, and Roberto Lopez-Solis. "A computational methodology for estimation of aerosol retention in a sand-bed based filtering system for severe accident venting strategies." Nuclear Technology and Radiation Protection 35, no. 2 (2020): 87–94. http://dx.doi.org/10.2298/ntrp2002087c.
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A computational methodology to estimate the capacity of aerosol particle retention in a filter- ing system based on sand bed is described in this work. This methodology uses a combination of computational fluid dynamics and mechanistic models in the calculation procedure. The methodology is applied to venting actions during a severe accident in a BWR Mark II primary containment. The SALOME and OpenFoam platforms were used to generate the geometric and numerical models of a full scale model of a sand bed filtering system. The Eulerian/Lagrangian approach was used to determine the steady-state of a compressible turbulent flow through a porous media and to compute the aerosol particle transport, respectively. Collection efficiency was calculated by means of a mechanistic model based on the capture efficiency of a single grain. The obtained Eulerian results include velocity, pressure, and temperature fields inside the filtering systems. The Lagrangian tracking of aerosol particles showed that particles crossing the coarser sand tend to accumulate initially on the periphery of the filter. The parametric studies showed that mass-flows of up to 4.7 kgs?1 satisfy the constraint of 1.1 bar pressure drop across the sand depth. Additionally, the efficiency of 99.5 % of retention was determined for 1.0 ?m aerosol particles in the 0.6 mm sand grain zone, for a gas velocity m of ms?1.
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Prada Botia, G. C., J. A. Pabón León, and M. S. Orjuela Abril. "Numerical simulation to analyze the physical behavior of centrifugal pumps as a turbine." Journal of Physics: Conference Series 2139, no. 1 (December 1, 2021): 012007. http://dx.doi.org/10.1088/1742-6596/2139/1/012007.
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Abstract In this research, a methodology based on the development of numerical simulations is proposed to analyze the physical behavior of centrifugal pumps such as a turbine. Numerical simulations were carried out using OpenFOAM software. For the validation of the numerical model, the construction of an experimental test bench was carried out. The analysis carried out involves the evaluation of performance parameters of the pump as a turbine, such as head, power, and efficiency. Additionally, the effect of the rotation speed on the previous parameters is evaluated. From the results obtained, it was shown that the maximum relative error was 4%, 3.4%, and 3.8% for the head, power, and efficiency parameters, respectively. In general, it was evidenced that the proposed numerical simulation has the ability to describe the real trends of the pump as a turbine for different flow conditions. In addition, an 11% increase in rotational speed was shown to cause a 12%, 1.9%, and 3% increase in head, power, and maximum efficiency. The proposed methodology is considered an adequate tool to analyze performance and identify the best efficiency point of pump systems such as a turbine. In this way, greater energy use is guaranteed.
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Kumaresh, Govindan Radhakrishnan, Ingar Fossan, Marutha Muthu Venkatraman, Knut Erik Giljarhus, Øystein Spangelo, and Stian Jensen. "CFD-Based Transient Ignition Probability Modeling of Gas Leaks in Enclosures." International Journal of Computational Methods 13, no. 02 (March 2016): 1640006. http://dx.doi.org/10.1142/s0219876216400065.
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Risk management of loss of containment at facilities processing or storing liquid flammable fluids is crucial in order to ensure safe operations. To control the risk, an extensive set of safety functions are in general implemented in design, for example systems that minimize the occurrence for initiating events (e.g., spontaneous leak of flammable material due to fatigue) and measures that reduce explosion loads arising in case of delayed ignition of the dispersed fluid mixed with air. Effective ventilation of the released fluid that potentially generates an explosive atmosphere (gas and/or droplets generated from the liquid phase) is one of the crucial barrier elements to mitigate the explosion hazard. Hence, the gas explosion hazard in enclosed modules with poor ventilation is of particular concern as a flammable mixture may accumulate even for small release rates. This may result in both high likelihood of ignition and considerable explosion loads in case of ignition due to the big amount of chemical energy taking part in the combustion process relative to the size of the enclosure. Computational fluid dynamics (CFD) methods are increasingly being used to characterize the consequences of leaks of flammable fluid in complex geometries, both modeling of the initial gas dispersion process and the resulting explosion and fire loads following from the combustion process in case of ignition. This paper presents an advanced methodology based on the CFD tool OpenFOAM for detailed assessment of the transient gas dispersion process and the associated likelihood of ignition for leaks of flammable fluid inside enclosures. The objective is to understand how to optimize the design of safety functions that affect the fire and explosion risk picture. This custom made tool, denoted cloudIgnitionFoam, accounts for the transient gas leak behavior based on real-time gas detection, subsequent initiation of emergency shutdown (ESD) and blow down systems and computes ignition probability based on the transient history of the dispersed gas cloud. The consistent methodology based on the CFD technology available in OpenFOAM and its ability to present the results in detail leverages the risk-based decision process. Measures that can be assessed quantitatively includes number and types of gas detectors and their optimal positioning, ignition source isolation, gas detection system voting philosophy, capacity of depressurization system and structural integrity of explosion barriers.
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Mavi, Anele, and Tiri Chinyoka. "Volume-of-Fluid Based Finite-Volume Computational Simulations of Three-Phase Nanoparticle-Liquid-Gas Boiling Problems in Vertical Rectangular Channels." Energies 15, no. 15 (August 8, 2022): 5746. http://dx.doi.org/10.3390/en15155746.
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This study develops robust numerical algorithms for the simulation of three-phase (solid-liquid-gas) boiling and bubble formation problems in rectangular channels. The numerical algorithms are based on the Finite Volume Methods (FVM) and implement both the volume-of-fluid (VOF) methods for liquid-gas interface tracking as well as the volume-fraction methods to account for the concentration of embedded solid nano-particles in the liquid phase. Water is used as the base-liquid and the solid phase is modelled via metallic nano-particles (both aluminium oxide and titanium oxide nano-particles are considered) that are homogeneously mixed within the liquid phase. The gas phase is considered as a vapour arising from the bolling processes of the liquid-phase. The finite volume methodology is implemented on the OpenFOAM software platform, specifically by careful modification and manipulation of existing OpenFOAM solvers. The governing fluid dynamical equations, for the three-phase boiling problem, take into account the thermal conductivity effects of the solid (nano-particle), the momentum and energy equations for both the liquid-phase and the gas-phase, and finally the decoupled mass conservation equations for the liquid- and gas- phases. The decoupled mass conservation equations are specifically used to model the phase change between the liquid- and gas- phases. In addition to the FVM and VOF numerical methodologies for the discretization of the governing equations, the pressure-velocity coupling is resolved via the PIMPLE algorithm, a combination of the Pressure Implicit with Splitting of Operator (PISO) and the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithms. The computational results are presented graphically with respect to variations in time as well as in the nano-particle volume fractions. The simulations and results accurately capture the formation of vapour bubbles in the two-phase (particle-free) liquid-gas flow and additionally the computational algorithms are similarly demonstrated to accurately illustrate and capture simulated boiling processes. The presence of the nano-particles is demonstrated to enhance the heat-transfer, boiling, and bubble formation processes.
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Olivares-Espinosa, Hugo, Simon-Philippe Breton, Karl Nilsson, Christian Masson, Louis Dufresne, and Stefan Ivanell. "Assessment of Turbulence Modelling in the Wake of an Actuator Disk with a Decaying Turbulence Inflow." Applied Sciences 8, no. 9 (September 1, 2018): 1530. http://dx.doi.org/10.3390/app8091530.
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The characteristics of the turbulence field in the wake produced by a wind turbine model are studied. To this aim, a methodology is developed and applied to replicate wake measurements obtained in a decaying homogeneous turbulence inflow produced by a wind tunnel. In this method, a synthetic turbulence field is generated to be employed as an inflow of Large-Eddy Simulations performed to model the flow development of the decaying turbulence as well as the wake flow behind an actuator disk. The implementation is carried out on the OpenFOAM platform, resembling a well-documented procedure used for wake flow simulations. The proposed methodology is validated by comparing with experimental results, for two levels of turbulence at inflow and disks with two different porosities. It is found that mean velocities and turbulent kinetic energy behind the disk are well estimated. The development of turbulence lengthscales behind the disk resembles what is observed in the free flow, predicting the ambient turbulence lengthscales to dominate across the wake, with little effect of shear from the wake envelope. However, observations of the power spectra confirm that shear yields a boost to the turbulence energy within the wake noticeable only in the low turbulence case. The results obtained show that the present implementation can successfully be used in the modelling and analysis of turbulence in wake flows.
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Silva, V. R., S. A. Verdério Júnior, C. Caminaga, and R. C. M. Neves. "STUDY AND VALIDATION OF MESHES IN TURBULENT ISOTHERMAL PROBLEMS OF NATURAL CONVECTION IN FLAT PLATES." Revista de Engenharia Térmica 20, no. 2 (July 28, 2021): 33. http://dx.doi.org/10.5380/reterm.v20i2.81785.
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The study of natural convection on flat plates is of great interest in the areas of Engineering, both for the simplicity of geometry and the wide variety of applications. In the study and definition of a numerical model, an ideal mesh configuration is the one that best represents physically, with minimal numerical influence and with the lowest computational cost, the problem addressed. The influence of two mesh configurations (non-uniform staggered and entirely uniform), at different refinement levels, was studied to evaluate natural convection heat transfer rates in flat plates of AR = 5; in isothermal conditions, in turbulent regime with the κ−ω SST RANS model and using free and open-source software OpenFOAM®. The physical-numerical methodology applied, and the numerical results obtained were validated from experimental results in the literature. The non-uniform staggered mesh configuration proved to be more adequate in precision, and computational cost to the problem situation studied. The entirely uniform mesh proved to be infeasible due to the high number of elements and computational cost demanded.
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Paula, Costa, Cataldo José, Mazaira Leorlen, González Daniel, Costa Alexandre, and Simões Teresa. "Wind Resource Assessment in Building Environment: Benchmarking of Numerical Approaches and Validation with Wind Tunnel Data." Wind 2, no. 4 (October 27, 2022): 659–90. http://dx.doi.org/10.3390/wind2040035.
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In the framework of the wind energy network for distributed generation in urban environments for most South American countries, wind resource assessment studies have been carried out in activities to establish a suitable methodology to assess the wind potential in urban environments. Some methodologies are already published in research studies, and the wind tunnel is the most accurate solution to obtain insight into the wind resource when measurements are unavailable, which is the most frequent case. Nevertheless, besides its validity, one cannot disregard the high cost of producing a scaled urban model and access to a wind tunnel. In this sense, this paper compares results from a wind tunnel experiment and different numerical modeling approaches. Two commercial models (WindSim and Wasp Engineering) and one open-source CFD code (OpenFOAM) are used. The results from the modeling simulation concluded that CFD models could achieve lower deviations for the mean wind speed and turbulence intensity when compared with non-CFD models. With such results, CFD modeling is a promising tool for reliably evaluating wind potential in urban environments.
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Xu, George, Arthur Lim, Harish Gopalan, Jing Lou, and Hee Joo Poh. "CFD Simulation of Chemical Gas Dispersion Under Atmospheric Boundary Conditions." International Journal of Computational Methods 17, no. 05 (May 10, 2019): 1940011. http://dx.doi.org/10.1142/s0219876219400115.
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Pollutant control is one of the key concerns in the design of buildings, for the sake of occupational health, safety and environment sustainability. In particular, risk analyses related to emergency leakage of chemicals from storage tanks or chemical processes have aroused increasing attentions in recent days, as well as the effectiveness of mitigation measures in order to eliminate, reduce and control the risks. In this paper, a CFD methodology with nonreactive chemical gases treated as passive scalars has been developed to simulate the gas dispersion across urban environments, subject to atmospheric boundary layer wind conditions. Special treatments to maintain the consistency in atmospheric boundary layer flow profiles, turbulence modeling and boundary conditions have also been accounted for. The proposed CFD methodology for gas dispersion has been implemented in the open source CFD code — OpenFOAM. It has been validated by modeling the gas dispersions for two urban-related test cases: the CODASC street canyon test case measured in a laboratory wind tunnel and the Mock Urban Setting Test (MUST) field experiment conducted in the desert area of Utah State. Effects of turbulent Schmidt number (Sct have been primarily addressed in this study. Statistical analyses about the discrepancies between predicted and experimental data have been carried out and statistical performance measures are used to quantify the accuracy of the proposed methodology. Simulations results from passive scalar transport equation demonstrate good agreement with experimental data, though tracer gases heavier than the atmospheric air were used in both the measurements. Furthermore, sensitivity tests also indicate that the accuracy of the simulation results is sensitive to the value of turbulent Schmidt number.
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Vargas, Guilherme Fuhrmeister, and Bruno Alvarez Scapin. "A numerical study on the wave loading on offshore structures of different cross-sectional geometries under the action of regular waves." Journal of Engineering and Exact Sciences 9, no. 5 (May 26, 2023): 15748–01. http://dx.doi.org/10.18540/jcecvl9iss5pp15748-01e.
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Coastal engineering and maritime hydraulics have experienced significant development over the years with the construction of bridges, oil exploration platforms, and ports, highlighting the importance of studying and quantifying the efforts resulting from wave loads on these structures. The present work aims to identify how a variation in the geometry of the cross-section, along the wave climate, can modify the magnitude of the wave loadings experienced by the structure. The open-source computational code OpenFOAM v. 4.1 was applied in the considered cases, along with the OlaFlow extension, considering the application of a structured mesh, the VOF (Volume of Fluid) methodology for representing the free surface, and the turbulence modeling according to Reynolds averaged equations (RANS). The results demonstrated that the shape of the cross-section plays an important role in the efforts experienced by the structure, and this influence is directly related to a characteristic length, whose intensification causes an increase in the magnitude of the experienced horizontal force. Likewise, by defining important dimensionless parameters, it was possible to obtain approximate expressions to determine the maximum wave force on the structures. The results and analyses carried out demonstrated that the force value calculated according to this approximation methodology is quite adequate, presenting relative errors smaller than 11,00%, corresponding to a relevant simplified approach for the determination of the maximum wave loads experienced by the structures, which can be important for proper design and analysis.
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Irsabudi, Andreas Maulana, Gaguk Jatisukamto, and Hary Sutjahjono. "Karakteristik Aerodinamika Pontoon Pesawat NXXX Versi Amfibi." Jurnal Rekayasa Mesin 12, no. 2 (August 15, 2021): 475–85. http://dx.doi.org/10.21776/ub.jrm.2021.012.02.24.
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Seaplanes are aircraft that can take off and landing on water. A seaplane’s requirement is its need to take off and landing on watery conditions which is equipped with a pontoon. Pontoon of a seaplane needs to be evaluated in terms of aerodynamics characteristics when a seaplane flies. The purpose of this study is to determine the correlation of various geometric combinations of deadrise angle, step height, and constant cross-section length with the values of coefficient of drag (CD), coefficient of lift (CL) and coefficient of moment (CM). The methodology was carried out by simulating Computational Fluid Dynamics (CFD) using OpenFOAM software. The results of this study could be concluded that deadrise angle affected coefficient of drag (CD), coefficient of lift (CL) and coefficient of moment (CM) with each value of 0.0055, 0.0044, -0.0036, while step height didn’t influence significantly on coefficient of drag (CD) and didn’t affect coefficient of lift (CL) and coefficient of moment (CM). Constant cross-section length didn’t affect significantly on coefficient of drag (CD) and coefficient of lift (CL) but increasing constant cross-section length increased coefficient of moment (CM) with a value of -0.0039.
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Petit, Olivier, and Håkan Nilsson. "Numerical Investigations of Unsteady Flow in a Centrifugal Pump with a Vaned Diffuser." International Journal of Rotating Machinery 2013 (2013): 1–14. http://dx.doi.org/10.1155/2013/961580.
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Computational fluid dynamics (CFD) analyses were made to study the unsteady three-dimensional turbulence in the ERCOFTAC centrifugal pump test case. The simulations were carried out using the OpenFOAM Open Source CFD software. The test case consists of an unshrouded centrifugal impeller with seven blades and a radial vaned diffuser with 12 vanes. A large number of measurements are available in the radial gap between the impeller and the diffuse, making this case ideal for validating numerical methods. Results of steady and unsteady calculations of the flow in the pump are compared with the experimental ones, and four different turbulent models are analyzed. The steady simulation uses the frozen rotor concept, while the unsteady simulation uses a fully resolved sliding grid approach. The comparisons show that the unsteady numerical results accurately predict the unsteadiness of the flow, demonstrating the validity and applicability of that methodology for unsteady incompressible turbomachinery flow computations. The steady approach is less accurate, with an unphysical advection of the impeller wakes, but accurate enough for a crude approximation. The different turbulence models predict the flow at the same level of accuracy, with slightly different results.
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Yan, Linbo, Ziyue Jia, Ziliang Wang, Boshu He, and Baizeng Fang. "Numerical Research on Biomass Gasification in a Quadruple Fluidized Bed Gasifier." Processes 10, no. 12 (November 28, 2022): 2526. http://dx.doi.org/10.3390/pr10122526.
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Utilization of bioenergy with carbon capture can realize carbon-negative syngas production. The quadruple fluidized bed gasifier (QFBG) integrates a chemical looping oxygen generation process and a dual fluidized bed gasifier with limestone as bed material. It is one promising device that can convert biomass to H2-rich syngas whilst capturing CO2 with little energy penalty. However, experimental or numerical simulation of QFBG is rarely reported on due to its complex structure, hindering the further commercialization and deployment of QFBG. In this work, a new computational fluid dynamics (CFD) solver is proposed to predict the complex physicochemical processes in QFBG based on the multi-phase particle in cell (MPPIC) methodology with the assistance of the open source software, OpenFOAM. The solver is first validated against experimental data in terms of hydrodynamics and reaction kinetics. Then, the solver is used to investigate the QFBG property. It is found that the QFBG can operate stably. The cold gas efficiency, H2 molar fraction, and CO2 capture rate of the QFBG are predicted to be 87.2%, 93.3%, and 90.5%, respectively, which is promising. It is believed that the solver can give reliable predictions for similar fluidized bed reactors.
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Barillari, Loris, Augusto Della Torre, Gianluca Montenegro, and Angelo Onorati. "CFD investigation of the radiative heat transfer effects on the adoption of an electrical heated catalyst to increase the abatement efficiency." Journal of Physics: Conference Series 2385, no. 1 (December 1, 2022): 012071. http://dx.doi.org/10.1088/1742-6596/2385/1/012071.
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Abstract The thermal transient of the after-treatment system (ATS) during the cold start and the typical urban drive low load engine operations is a crucial point for the conversion efficiency. In this context, the adoption of electrical heating is regarded as an effective solution to promote the catalytic activity and the pollutants abatement. This paper focuses on the evaluation of the radiative heat transfer affecting the operation of an electrical heated catalyst employed to increase the abatement efficiency of a standard catalyst. The modeling methodology relies on a CFD framework based on a Conjugate Heat Transfer (CHT) approach in OpenFOAM, so that a detailed characterization of the thermal transient of the different components of the exhaust line can be achieved. The electrical heating device under investigation is based on a metallic support and it is heated by the Joule effect. The distribution of the heat and its subsequent interaction with the gas flow significantly influence the catalyst operations. In this context, the CFD modeling framework has been further developed so that it is possible to accurately evaluate the radiative heat transfer in correspondence of the porous regions. The description of such features is mandatory for an accurate prediction of the maximum electrical heating device temperatures, resulting in a reliable estimation of the gas flow temperature and its subsequent interaction with the catalyst. The simulation methodology has been applied at first excluding the radiative heat transfer. Then, the developed radiation modeling is applied, so that its influence on the ATS performance can be fully evaluated.
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Fadiga, Ettore, Nicola Casari, Alessio Suman, and Michele Pinelli. "Structured Mesh Generation and Numerical Analysis of a Scroll Expander in an Open-Source Environment." Energies 13, no. 3 (February 4, 2020): 666. http://dx.doi.org/10.3390/en13030666.
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The spread of the organic rankine cycle applications has driven researchers and companies to focus on the improvement of their performance. In small to medium-sized plants, the expander is the component that has typically attracted the most attention. One of the most used types of machine in this scenario is the scroll. Among the other methods, numerical analyses have been increasingly exploited for the investigation of the machine’s behaviour. Nonetheless, there are major challenges for the successful application of computational fluid dynamics (CFD) to scrolls. Specifically, the dynamic mesh treatment required to capture the movement of working chambers and the nature of the expanding fluids require special care. In this work, a mesh generator for scroll machines is presented. Given few inputs, the software described provides the mesh and the nodal positions required for the evolution of the motion in a predefined mesh motion approach. The mesh generator is developed ad hoc for the coupling with the open-source CFD suite OpenFOAM. A full analysis is then carried out on a reverse-engineered commercial machine, including the refrigerant properties calculations via CoolProp. It is demonstrated that the proposed methodology allows for a fast simulation and achieves a good agreement with respect to former analyses.
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Vyzikas, Thomas, Dimitris Stagonas, Christophe Maisondieu, and Deborah Greaves. "Intercomparison of Three Open-Source Numerical Flumes for the Surface Dynamics of Steep Focused Wave Groups." Fluids 6, no. 1 (December 30, 2020): 9. http://dx.doi.org/10.3390/fluids6010009.
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NewWave-type focused wave groups are commonly used to simulate the design wave for a given sea state. These extreme wave events are challenging to reproduce numerically by the various Numerical Wave Tanks (NWTs), due to the high steepness of the wave group and the occurring wave-wave interactions. For such complex problems, the validation of NWTs against experimental results is vital for confirming the applicability of the models. Intercomparisons among different solvers are also important for selecting the most appropriate model in terms of balancing between accuracy and computational cost. The present study compares three open-source NWTs in OpenFOAM, SWASH and HOS-NWT, with experimental results for limiting breaking focused wave groups. The comparison is performed by analysing the propagation of steep wave groups and their extracted harmonics after employing an accurate focusing methodology. The scope is to investigate the capabilities of the solvers for simulating extreme NewWave-type groups, which can be used as the “design wave” for ocean and coastal engineering applications. The results demonstrate the very good performance of the numerical models and provide valuable insights to the design of the NWTs, while highlighting potential limitations in the reproduction of specific harmonics of the wave group.
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Vargas, Guilherme Fuhrmeister, Edith Beatriz Camaño Schettini, and Bruno Alavarez Scapin. "Dynamics of an oscillating wave surge converter: an analysis on the influence of the bottom slope." South Florida Journal of Development 4, no. 1 (February 28, 2023): 330–43. http://dx.doi.org/10.46932/sfjdv4n1-024.
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The Oscillating Wave Surge Converter represents a technology with great potential for generating electricity from ocean waves, promoting energy continuously throughout a day. Its development is on a pre-commercial scale and has been encouraging several companies and institutions to invest in the improvement and study of this conversion system. Simulations in Computational Fluid Dynamics are very important tools for the development of these converters, since they provide essential details for the analysis of the variables that influence the system. In this context, the present work uses the Large Eddy Simulation modeling to study the influence of the bottom slope on the device dynamics, which is performed using the OpenFOAM v.4.1 computational code and its extension OlaFlow. The model used in the analysis is two-dimensional and based on the Wall-Adapting Local Eddy-Viscosity methodology, while a structured mesh is applied. Through a detailed analysis, it was observed that the converter hydrodynamics is strongly influenced by the bottom slope, which is responsible for the intensification of the captured power in regions with slopes lower than 5º, and for the power decrease in cases where the slope exceeds 15º. Significant increases in slope can cause a decrease up to 28% in the converter excitation torque, significantly affecting its performance in electric power generation.
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Vargas, Guilherme Fuhrmeister, and Alexandre Beluco. "Dissertation Overview: Numerical modelling of the hydrodynamics and energy generation of an oscillating wave surge converter system." Journal of Engineering and Exact Sciences 9, no. 4 (May 24, 2023): 15795–01. http://dx.doi.org/10.18540/jcecvl9iss4pp15795-01d.
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The Oscillating Wave Surge Converter (OWSC) is one of the most relevant systems for harnessing energy from ocean waves, generating energy by capturing the horizontal component of wave motion. This technology, which is on a pre-commercial development scale, presents one of the greatest potentials for electricity generation, due to its operating principle and the great improvement in design experienced over the last few years. Today, Computational numerical modelling is one of the main tools for the study and design of this and several other power generation systems from sea waves. In this context, a detailed study of a wave farm composed of several OWSCs is necessary, which represents a case closer to reality, since most renewable systems include several modules of the same converter. Considering the complexity of the existing hydrodynamics in these cases, a numerical modeling methodology based on the Large Eddy Simulation (LES) methodology is applied to correctly represent the oscillation of the structure and the observed flow fields. In order to achieve the objectives, the OpenFOAM v.4.1 computational code and the OlaFlow extension are used, together with the Wall Adapting Local Eddy Viscosity (WALE) LES model, which allows a representation of the system very close to real application cases. The proposed model demonstrated a good adherence of the results when compared to experimental studies present in the literature. Likewise, it was observed that changes in wave height and period, bottom slope, wave reflection, spacing between converters, and the wave farm layout can cause important variations in the energy generated by the system, increasing or reducing considerably its efficiency, emphasizing the importance of these parameters in the design and development of this technology.
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Vargas, Guilherme Fuhrmeister, and Alexandre Beluco. "Thesis Overview: Oscillating wave surge converters – Large eddy simulation modelling of wave farms hydrodynamics and its related energy potential." Journal of Engineering and Exact Sciences 9, no. 3 (May 7, 2023): 15780–01. http://dx.doi.org/10.18540/jcecvl9iss3pp15780-01t.
Full textAbstract:
The Oscillating Wave Surge Converter (OWSC) is one of the most relevant systems for harnessing energy from ocean waves, generating energy by capturing the horizontal component of wave motion. This technology, which is on a pre-commercial development scale, presents one of the greatest potentials for electricity generation, due to its operating principle and the great improvement in design experienced over the last few years. Today, Computational numerical modelling is one of the main tools for the study and design of this and several other power generation systems from sea waves. In this context, a detailed study of a wave farm composed of several OWSCs is necessary, which represents a case closer to reality, since most renewable systems include several modules of the same converter. Considering the complexity of the existing hydrodynamics in these cases, a numerical modeling methodology based on the Large Eddy Simulation (LES) methodology is applied to correctly represent the oscillation of the structure and the observed flow fields. In order to achieve the objectives, the OpenFOAM v.4.1 computational code and the OlaFlow extension are used, together with the Wall Adapting Local Eddy Viscosity (WALE) LES model, which allows a representation of the system very close to real application cases. The proposed model demonstrated a good adherence of the results when compared to experimental studies present in the literature. Likewise, it was observed that changes in wave height and period, bottom slope, wave reflection, spacing between converters, and the wave farm layout can cause important variations in the energy generated by the system, increasing or reducing considerably its efficiency, emphasizing the importance of these parameters in the design and development of this technology.
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Lewandowski, Michał T., Paweł Płuszka, and Jacek Pozorski. "Influence of inlet boundary conditions in computations of turbulent jet flames." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 6 (June 4, 2018): 1433–56. http://dx.doi.org/10.1108/hff-02-2017-0078.
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Purpose This paper aims to assess the sensitivity of numerical simulation results of turbulent reactive flow to the formulation of inlet boundary conditions. The analysis concerns the profiles of the mean velocity the turbulence kinetic energy k and its dissipation rate ϵ. It is intended to provide guidance to the determination of inlet conditions when only global flow data are available. This situation can be met both in simple laboratory experiments and in industrial full-scale applications, when measurements are either incomplete or infeasible, resulting in lack of detailed inlet data. Design/methodology/approach Two turbulence–chemistry interaction models were studied: eddy dissipation concept and partially stirred reactor. Three different velocity profiles and related turbulence statistics were applied to present feasible scenarios and their consequences. Simulations with the most appropriate inlet data were accompanied with profiles of turbulent quantities obtained with a proposed method. This method was contrasted to other approaches popular in the literature: the pre-inlet pipe and the separate cold flow simulations of a burner. The methodology was validated on two laboratory-scale jet flames: Delft Jet-in-Hot-Coflow and Sandia CHN B. The simulations were carried out with open source code OpenFOAM. Findings The proposed relations for turbulence kinetic energy and its dissipation rate at the inlet are found to provide results comparable to those obtained with the use of experimental data as inlet boundary conditions. Moreover, from a certain location downstream the jet, weakly dependent on the Reynolds number, the influence of inlet conditions on flow statistics was found to be negligible. Originality/value This work reveals the consequences of the use of rather crude assumptions made for inlet boundary conditions. Proposed formulas for the profiles for k and epsilon are attractive alternatives to other approaches aiming to determine the inlet boundary conditions for turbulent jet flows.
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Gopal, Jaya Madana, Giovanni Tretola, Robert Morgan, Guillaume de Sercey, Andrew Atkins, and Konstantina Vogiatzaki. "Understanding Sub and Supercritical Cryogenic Fluid Dynamics in Conditions Relevant to Novel Ultra Low Emission Engines." Energies 13, no. 12 (June 12, 2020): 3038. http://dx.doi.org/10.3390/en13123038.
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In this paper we provide insight into the thermophysical properties and the dynamics of cryogenic jets. The motivation of the work is to optimise the use of cryogenic fluids in novel ultra low emission engines. For demonstration, we use conditions relevant to an internal combustion engine currently being developed by Dolphin N2 and the University of Brighton, the CryoPower recuperated split cycle engine (RSCE). The principle of this engine is a split-cycle combustion concept which can use cryogenic injection in the compression cylinder to achieve isothermal compression and thus help maximise the efficiency of the engine. Combined experimental and numerical findings are presented and the effects of atomisation dynamics of the LN 2 are explored at both sub- and supercritical conditions in order to cover different pressure and temperature conditions representative of the engine compression cycle. For subcritical regimes, we observe that the appearance of the jet coincides with the predicted atomisation regimes based on the Weber, Ohnesorge and Reynolds numbers for other common fluids. For the modelling of supercritical jets, a new methodology within OpenFoam which accounts for Real Fluid Thermodynamics has been developed and the jet behaviour under various pressure and temperature conditions has been investigated. To our knowledge this is the first study where a cryogenic spray process evolution is examined for conditions relevant to the ones prevailing in a compression chamber accounting for both sub and supercritical conditions.
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Mavi, Anele, Tiri Chinyoka, and Andrew Gill. "Modelling and Analysis of Viscoelastic and Nanofluid Effects on the Heat Transfer Characteristics in a Double-Pipe Counter-Flow Heat Exchanger." Applied Sciences 12, no. 11 (May 28, 2022): 5475. http://dx.doi.org/10.3390/app12115475.
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This study computationally investigates the heat transfer characteristics in a double-pipe counter-flow heat-exchanger. A heated viscoelastic fluid occupies the inner core region, and the outer annulus is filled with a colder Newtonian-Fluid-Based Nanofluid (NFBN). A mathematical model is developed to study the conjugate heat transfer characteristics and heat exchange properties from the hot viscoelastic fluid to the colder NFBN. The mathematical modelling and formulation of the given problem comprises of a system of coupled nonlinear partial differential Equations (PDEs) governing the flow, heat transfer, and stress characteristics. The viscoelastic stress behaviour of the core fluid is modelled via the Giesekus constitutive equations. The mathematical complexity arising from the coupled system of transient and nonlinear PDEs makes them analytically intractable, and hence, a recourse to numerical and computational methodologies is unavoidable. A numerical methodology based on the finite volume methods (FVM) is employed. The FVM algorithms are computationally implemented on the OpenFOAM software platform. The dependence of the field variables, namely the velocity, temperature, pressure, and polymeric stresses on the embedded flow parameters, are explored in detail. In particular, the results illustrate that an increase in the nanoparticle volume-fraction, in the NFBN, leads to enhanced heat-exchange characteristics from the hot core fluid to the colder shell NFBN. Specifically, the results illustrate that the use of NFBN as the coolant fluid leads to enhanced cooling of the hot core-fluid as compared to using an ordinary (nanoparticle free) Newtonian coolant.
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Nering, Konrad, and Kazimierz Rup. "Modified algebraic model of laminar-turbulent transition for internal flows." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 4 (January 21, 2019): 1743–53. http://dx.doi.org/10.1108/hff-10-2018-0597.
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Purpose For internal flows with small values of the Reynolds number, there is often at a considerable distance from the pipe inlet cross-section a change of the flow form from laminar to turbulent. To describe this phenomenon of laminar-turbulent transition in the pipe, also parallel-plate channel flow, a modified algebraic intermittency model was used. The original model for bypass transition developed by S. Kubacki and E. Dick was designed for simulating bypass transition in turbomachinery. Design/methodology/approach A modification of mentioned model was proposed. Modified model is suitable for simulating internal flows in pipes and parallel-plate channels. Implementation of the modified model was made using the OpenFOAM framework. Values of several constants of the original model were modified. Findings For selected Reynolds numbers and turbulence intensities (Tu), localization of laminar breakdown and fully turbulent flow was presented. Results obtained in this work were compared with corresponding experimental results available in the literature. It is particularly worth noting that asymptotic values of wall shear stress in flow channels and asymptotic values of axis velocity obtained during simulations are similar to related experimental and theoretical results. Originality/value The modified model allows precision numerical simulation in the area of transitional flow between laminar, intermittent and turbulent flows in pipes and parallel-plate channels. Proposed modified algebraic intermittency model presented in this work is described by a set of two additional partial differential equations corresponding with k-omega turbulence model presented by Wilcox (Wilcox, 2006).
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Abdessemed, Chawki, Yufeng Yao, Abdessalem Bouferrouk, and Pritesh Narayan. "Morphing airfoils analysis using dynamic meshing." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 5 (May 8, 2018): 1117–33. http://dx.doi.org/10.1108/hff-06-2017-0261.
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Purpose The purpose of this paper is to use dynamic meshing to perform CFD analyses of a NACA 0012 airfoil fitted with a morphing trailing edge (TE) flap when it undergoes static and time-dependent morphing. The steady CFD predictions of the original and morphing airfoils are validated against published data. The study also investigates an airfoil with a hinged TE flap for aerodynamic performance comparison. The study further extends to an unsteady CFD analysis of a dynamically morphing TE flap for proof-of-concept and also to realise its potential for future applications. Design/methodology/approach An existing parametrization method was modified and implemented in a user-defined function (UDF) to perform dynamic meshing which is essential for morphing airfoil unsteady simulations. The results from the deformed mesh were verified to ensure the validity of the adopted mesh deformation method. ANSYS Fluent software was used to perform steady and unsteady analysis and the results were compared with computational predictions. Findings Steady computational results are in good agreement with those from OpenFOAM for a non-morphing airfoil and for a morphed airfoil with a maximum TE deflection equal to 5 per cent of the chord. The results obtained by ANSYS Fluent show that an average of 6.5 per cent increase in lift-to-drag ratio is achieved, compared with a hinged flap airfoil with the same TE deflection. By using dynamic meshing, unsteady transient simulations reveal that the local flow field is influenced by the morphing motion. Originality/value An airfoil parametrisation method was modified to introduce time-dependent morphing and used to drive dynamic meshing through an in-house-developed UDF. The morphed airfoil’s superior aerodynamic performance was demonstrated in comparison with traditional hinged TE flap. A methodology was developed to perform unsteady transient analysis of a morphing airfoil at high angles of attack beyond stall and to compare with published data. Unsteady predictions have shown signs of rich flow features, paving the way for further research into the effects of a dynamic flap on the flow physics.
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Groth, Corrado, Emiliano Costa, and Marco Evangelos Biancolini. "RBF-based mesh morphing approach to perform icing simulations in the aviation sector." Aircraft Engineering and Aerospace Technology 91, no. 4 (April 1, 2019): 620–33. http://dx.doi.org/10.1108/aeat-07-2018-0178.
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Purpose Numerical simulation of icing has become a standard. Once the iced shape is known, however, the analyst needs to update the computational fluid dynamics (CFD) grid. This paper aims to propose a method to update the numerical mesh with ice profiles. Design/methodology/approach The present paper concerns a novel and fast radial basis functions (RBF) mesh morphing technique to efficiently and accurately perform ice accretion simulations on industrial models in the aviation sector. This method can be linked to CFD analyses to dynamically reproduce the ice growth. Findings To verify the consistency of the proposed approach, one of the most challenging ice profile selected in the LEWICE manual was replicated and simulated through CFD. To showcase the effectiveness of this technique, predefined ice profiles were automatically applied on two-dimensional (2D) and three-dimensional (3D) cases using both commercial and open-source CFD solvers. Practical implications If ice accreted shapes are available, the meshless characteristic of the proposed approach enables its coupling with the CFD solvers currently supported by the RBF4AERO platform including OpenFOAM, SU2 and ANSYS Fluent. The advantages provided by the use of RBF are the high performance and reliability, due to the fast application of mesh smoothing and the accuracy in controlling surface mesh nodes. Originality/value As far as authors’ knowledge is concerned, this is the first time in scientific literature that RBF are proposed to handle icing simulations. Due to the meshless characteristic of the RBF mesh morphing, the proposed approach is cross solver and can be used for both 2D and 3D geometries.
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Castillo-Sánchez, Hugo A., Leandro F. de Souza, and Antonio Castelo. "Numerical Simulation of Rheological Models for Complex Fluids Using Hierarchical Grids." Polymers 14, no. 22 (November 16, 2022): 4958. http://dx.doi.org/10.3390/polym14224958.
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In this work, we implement models that are able to describe complex rheological behaviour (such as shear-banding and elastoviscoplasticity) in the HiGTree/HiGFlow system, which is a recently developed Computational Fluid Dynamics (CFD) software that can simulate Newtonian, Generalised-Newtonian and viscoelastic flows using finite differences in hierarchical grids. The system uses a moving least squares (MLS) meshless interpolation technique, allowing for more complex mesh configurations while still keeping the overall order of accuracy. The selected models are the Vasquez-Cook-McKinley (VCM) model for shear-banding micellar solutions and the Saramito model for viscoelastic fluids with yield stress. Development of solvers and numerical simulations of inertial flows of these models in 2D channels and planar-contraction 4:1 are carried out in the HiGTree/HiGFlow system. Our results are compared with those predicted by two other methodologies: the OpenFOAM-based software RheoTool that uses the Finite-Volume-Method and an in-house code that uses the Vorticity-Velocity-Formulation (VVF). We found an excellent agreement between the numerical results obtained by these three different methods. A mesh convergence analysis using uniform and refined meshes is also carried out, where we show that great convergence results in tree-based grids are obtained thanks to the finite difference method and the meshless interpolation scheme used by the HiGFlow software. More importantly, we show that our methodology implemented in the HiGTreee/HiGFlow system can successfully reproduce rheological behaviour of high interest by the rheology community, such as non-monotonic flow curves of micellar solutions and plug-flow velocity profiles of yield-stress viscoelastic fluids.
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Corzo, Santiago Francisco, Damian Enrique Ramajo, and Norberto Marcelo Nigro. "High-Rayleigh heat transfer flow." International Journal of Numerical Methods for Heat & Fluid Flow 27, no. 9 (September 4, 2017): 1928–54. http://dx.doi.org/10.1108/hff-05-2016-0176.
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Purpose The purpose of this paper is to assess the Boussinesq approach for a wide range of Ra (10 × 6 to 10 × 11) in two-dimensional (square cavity) and three-dimensional (cubic cavity) problems for air- and liquid-filled domains. Design/methodology/approach The thermal behavior in “differentially heated cavities” filled with air (low and medium Rayleigh) and water (high Rayleigh) is solved using computational fluid dynamics (CFDs) (OpenFOAM) with a non-compressible (Boussinesq) and compressible approach (real water properties from the IAPWS database). Findings The results from the wide range of Rayleigh numbers allowed for the establishment of the limitation of the Boussinesq approach in problems where the fluid has significant density changes within the operation temperature range and especially when the dependence of density with temperature is not linear. For these cases, the symmetry behavior predicted by Boussinesq is far from the compressible results, thus inducing a transient heat imbalance and leading to a higher mean temperature. Research limitations/implications The main limitation of the present research can be found in the shortage of experimental data for very high Rayleigh problems. Practical implications Practical implications of the current research could be use of the Boussinesq approach by carefully observing its limitations, especially for sensible problems such as the study of pressure vessels, nuclear reactors, etc. Originality/value The originality of this paper lies in addressing the limitations of the Boussinesq approach for high Rayleigh water systems. This fluid is commonly used in numerous industrial equipment. This work presents valuable conclusions about the limitations of the currently used models to carry out industrial simulations.