Journal articles: 'Simulation URANS'

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Ehrle, Maximilian, Andreas Waldmann, Thorsten Lutz, and Ewald Krämer. "Simulation of transonic buffet with an automated zonal DES approach." CEAS Aeronautical Journal 11, no. 4 (September 1, 2020): 1025–36. http://dx.doi.org/10.1007/s13272-020-00466-7.

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Abstract A study of transonic buffet on the NASA Common Research Model at flight Reynolds numbers is presented. The ability of two different hybrid RANS/LES models as well as the URANS approach for resolving three-dimensional buffet motion was evaluated by means of spectral analysis. Automated Zonal DES and URANS simulations show similar results in terms of buffet frequency and spanwise propagation of buffet cells, whereas the Delayed Detached Eddy Simulation results indicate a strong interaction between flow separation and shock motion. The extracted characteristic frequencies which are associated with transonic buffet are located in a range of Sr = 0.2–0.65 for URANS and AZDES and are therefore in accordance with findings from related recent research. Furthermore, the simulation time series were investigated and a structure of spanwise moving buffet cells with varying convection speed and wavelength could be observed.

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Escarti-Guillem, Mara S., Sergio Hoyas, and Luis M. García-Raffi. "Rocket plume URANS simulation using OpenFOAM." Results in Engineering 4 (December 2019): 100056. http://dx.doi.org/10.1016/j.rineng.2019.100056.

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Kim, Changhee, and Changmin Son. "Comparative Study on Steady and Unsteady Flow in a Centrifugal Compressor Stage." International Journal of Aerospace Engineering 2019 (June 9, 2019): 1–12. http://dx.doi.org/10.1155/2019/9457249.

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Steady Reynolds-averaged Navier-Stokes (RANS) simulation with the mixing-plane approach is the most common procedure to obtain the performance of a centrifugal compressor in an industrial development process. However, the accurate prediction of complicated flow fields in centrifugal compressors is the most significant challenge. Some phenomena such as the impeller-diffuser flow interaction generates the unsteadiness which can affect the steady assumption. The goal of this study is to investigate the differences between the RANS and URANS simulation results in a centrifugal compressor stage. Simulations are performed at three operating points: near surge (NS), design point (DP), and near choke (NC). The results show that the RANS simulation can predict the overall performance with reasonable accuracy. However, the differences between the RANS and URANS simulation are quite significant especially in the region that the flows are highly unsteady or nearly separated. The RANS simulation is still not very accurate to predict the time-dependent quantities of the flow structure. It shows that the URANS calculations are necessary to predict the detailed flow structures and performance. The phenomena and mechanisms of the complex and highly unsteady flow in the centrifugal compressor with a vaned diffuser are presented and analyzed in detail.

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Chang, Kyoungsik, George Constantinescu, and Seung-O. Park. "Assessment of Predictive Capabilities of Detached Eddy Simulation to Simulate Flow and Mass Transport Past Open Cavities." Journal of Fluids Engineering 129, no. 11 (June 5, 2007): 1372–83. http://dx.doi.org/10.1115/1.2786529.

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The three-dimensional (3D) incompressible flow past an open cavity in a channel is predicted using the Spalart–Almaras (SA) and the shear-stress-transport model (SST) based versions of detached eddy simulation (DES). The flow upstream of the cavity is fully turbulent. In the baseline case the length to depth (L∕D) ratio of the cavity is 2 and the Reynolds number ReD=3360. Unsteady RANS (URANS) is performed to better estimate the performance of DES using the same code and meshes employed in DES. The capabilities of DES and URANS to predict the mean flow, velocity spectra, Reynolds stresses, and the temporal decay of the mass of a passive contaminant introduced instantaneously inside the cavity are assessed based on comparisons with results from a well resolved large eddy simulation (LES) simulation of the same flow conducted on a very fine mesh and with experimental data. It is found that the SA-DES simulation with turbulent fluctuations at the inlet gives the best overall predictions for the flow statistics and mass exchange coefficient characterizing the decay of scalar mass inside the cavity. The presence of inflow fluctuations in DES is found to break the large coherence of the vortices shed in the separated shear layer that are present in the simulations with steady inflow conditions and to generate a wider range of 3D eddies inside the cavity, similar to LES. The predictions of the mean velocity field from URANS and DES are similar. However, URANS predictions show poorer agreement with LES and experiment compared to DES for the turbulence quantities. Additionally, simulations with a higher Reynolds number (ReD=33,600) and with a larger length to depth ratio (L∕D=4) are conducted to study the changes in the flow and shear-layer characteristics, and their influence on the ejection of the passive contaminant from the cavity.

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Nakayama, A., and K. Miyashita. "URANS simulation of flow over smooth topography." International Journal of Numerical Methods for Heat & Fluid Flow 11, no. 8 (December 2001): 723–45. http://dx.doi.org/10.1108/09615530110409394.

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Merzari, E., H. Ninokata, R. Mereu, E. Colombo, and F. Inzoli. "URANS Simulation of Confined Parallel Jet Mixing." Nuclear Technology 175, no. 3 (September 2011): 538–52. http://dx.doi.org/10.13182/nt10-148.

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Yang, Guangjun, Xiaoxiao Li, Li Ding, Fahua Zhu, Zhigang Wang, Sheng Wang, Zhen Xu, Jingxin Xu, Pengxiang Qiu, and Zhaobing Guo. "CFD Simulation of Pollutant Emission in a Natural Draft Dry Cooling Tower with Flue Gas Injection: Comparison between LES and RANS." Energies 12, no. 19 (September 24, 2019): 3630. http://dx.doi.org/10.3390/en12193630.

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Accurate prediction of pollutant dispersion is vital to the energy industry. This study investigated the Computational Fluid Dynamics (CFD) simulation of pollutant emission in a natural draft dry cooling tower (NDDCT) with flue gas injection. In order to predict the diffusion and distribution characteristics of the pollutant more accurately, Large Eddy Simulation (LES) was applied to predict the flow field and pollutant concentration field and compared with Reynolds Average Navier-Stokes (RANS) and Unsteady Reynolds Average Navier-Stokes (URANS). The relationship between pollutant concentration pulsation and velocity pulsation is emphatically analyzed. The results show that the flow field and concentration field simulated by RANS and URANS are very close, and the maximum value of LES is about 43 times that of RANS and URANS for the prediction of pollutant concentration in the inner shell of cooling tower. Pollutant concentration is closely related to local flow field velocity. RANS and URANS differ greatly from LES in flow field prediction, especially at the outlet and downwind of cooling tower. Compared with URANS, LES can simulate flow field pulsation with a smaller scale and higher frequency.

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Salunkhe, Sanchit, Oumnia El Fajri, Shanti Bhushan, David Thompson, Daphne O’Doherty, Tim O’Doherty, and Allan Mason-Jones. "Validation of Tidal Stream Turbine Wake Predictions and Analysis of Wake Recovery Mechanism." Journal of Marine Science and Engineering 7, no. 10 (October 11, 2019): 362. http://dx.doi.org/10.3390/jmse7100362.

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This paper documents the predictive capability of rotating blade-resolved unsteady Reynolds averaged Navier-Stokes (URANS) and Improved Delayed Detached Eddy Simulation (IDDES) computations for tidal stream turbine performance and intermediate wake characteristics. Ansys/Fluent and OpenFOAM simulations are performed using mixed-cell, unstructured grids consisting of up to 11 million cells. The thrust, power and intermediate wake predictions compare reasonably well within 10% of the experimental data. For the wake predictions, OpenFOAM performs better than Ansys/Fluent, and IDDES better than URANS when the resolved turbulence is triggered. The primary limitation of the simulations is under prediction of the wake diffusion towards the turbine axis, which in return is related to the prediction of turbulence in the tip-vortex shear layer. The shear-layer involves anisotropic turbulent structures; thus, hybrid RANS/LES models, such as IDDES, are preferred over URANS. Unfortunately, IDDES fails to accurately predict the resolved turbulence in the near-wake region due to the modeled stress depletion issue.

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Martineau Rousseau, Philippe, Azzeddine Soulaïmani, and Michel Sabourin. "Efficiency Assessment for Rehabilitated Francis Turbines Using URANS Simulations." Water 13, no. 14 (July 7, 2021): 1883. http://dx.doi.org/10.3390/w13141883.

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Due to the large number of aging hydraulic turbines in North America, rehabilitation is a growing market as these turbines have low efficiency compared to modern ones. Computational Fluid Dynamics identifies components with poor hydraulic performance. The models often used in industry are based on individually analyzing the sub-components of a turbine instead of full turbine simulations due to computational and time limitations. An industrial case has shown that such analyses may lead to underestimating the efficiency increases by modifying the stay vane. The unsteady full turbine simulation proposes to simulate all components simultaneously to assess this efficiency augmentation due to stay vane rehabilitation. The developed simulation methodology is used to evaluate the efficiency increase and the flow of two rehabilitated turbines with stay vane modifications. Comparison with model tests shows the accuracy of the simulations. However, the methodology used shows imprecision in predicting the efficiency increase compared to model tests. Further works should consider the use of more complex flow modeling methods to measure the efficiency increase by the stay vane modifications.

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Kratzsch, Christoph, Amjad Asad, and Rüdiger Schwarze. "CFD of the MHD Mold Flow by Means of Hybrid LES/RANS Turbulence Modeling." Journal for Manufacturing Science and Production 15, no. 1 (March 31, 2015): 49–57. http://dx.doi.org/10.1515/jmsp-2014-0046.

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AbstractIn the last decades, electromagnetic braking (EMBr) systems become a powerful tool to dampen possible jet oscillations in the continuous casting mold. Further studies showed that if a EMBr is not positioned correctly, it can induce flow oscillations. Hence, the design of these braking systems can be promoted by adequate CFD simulations. In most cases, unsteady RANS simulations (URANS) are sufficient to resolve low-frequency, large-scale oscillations of these MHD flows. Alternatively, Large Eddy Simulations (LES) may also resolve important details of the turbulence. However, since they require much finer computational grids, the computational costs are much higher. A bridge between both approaches are hybrid methods like the Scale Adaptive Simulation (SAS). In this study, we compare the performance of SAS with URANS and LES. Results are validated in detail by comparison with data from a Ruler-EMBr model experiment.

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11

Krastev, Vesselin Krassimirov, Giovanni Di Ilio, Clara Iacovano, Alessandro d’Adamo, and Stefano Fontanesi. "Standard and consistent Detached-Eddy Simulation for turbulent engine flow modeling: an application to the TCC-III engine." E3S Web of Conferences 197 (2020): 06021. http://dx.doi.org/10.1051/e3sconf/202019706021.

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Multidimensional modeling of Cycle-to-Cycle Variability (CCV) has become a crucial support for the development and optimization of modern direct-injection turbocharged engines. In that sense, the only viable modeling options is represented by scale-resolving approaches such as Large Eddy Simulation (LES) or hybrid URANS/LES methods. Among other hybrid approaches, Detached-Eddy Simulation (DES) has the longest development story and is therefore commonly regarded as the most reliable choice for engineering-grade simulation. As such, in the last decade DESbased methods have found their way through the engine modeling community, showing a good potential in describing turbulence-related CCV in realistic engine configurations and at reasonable computational costs. In the present work we investigate the in-cylinder modeling capabilites of a standard two-equation DES formulation, compared to a more recent one which we call DESx. The DESx form differs from standard DES in the turbulent viscosity switch from URANS to LES-like behavior, which for DESx is fully consistent with Yoshizawa’s one-equation sub-grid scale model. The two formulations are part of a more general Zonal-DES (ZDES) methodology, developed and validated by the authors in a series of previous publications. Both variants are applied to the multi-cycle simulation of the TCC-III experimental engine setup, using sub-optimal grid refinement levels in order to stress the model limitations in URANS-like numerical resolution scenarios. Outcomes from this study show that, although both alternatives are able to ouperform URANS even in coarse grid arrangements, DESx emerges as sligthly superior and thus it can be recommended as the default option for in-cylinder flow simulation.

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12

Eghbalzade, A., M. M. Namin, S. A. A. Salehi, B. Firoozabad, and M. Javan. "URANS Simulation of 2D Continuous and Discontinuous Gravity Currents." Journal of Applied Sciences 8, no. 16 (August 1, 2008): 2801–13. http://dx.doi.org/10.3923/jas.2008.2801.2813.

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13

Stalewski, Wieńczysław, Wiesław Zalewski, Katarzyna Surmacz, Maximilian Pulfer, and Frieder Hirsch. "Computational Simulation of Fully Trimmed Flight of a Helicopter in Hover." Journal of KONES 26, no. 1 (March 1, 2019): 175–81. http://dx.doi.org/10.2478/kones-2019-0021.

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Abstract In trimmed flight of a helicopter, all the forces and moments, aerodynamic, inertial, and gravitational, are in balance. Keeping the helicopter in trimmed state, needs a precise adjustment of flight controls. The methodology of simulation of a fully trimmed flight of rotorcraft has been developed and applied to simulate hover of a helicopter. The presented approach is based on a solution of Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. In contrast to typical solutions of such problem, in the newly developed methodology, the flight controls corresponding to the trimmed-flight conditions are also determined based on the solution of URANS equations. The methodology is based on coupling of several computational models of Computational Fluid Dynamics and Flight Dynamic. The URANS equations are solved in a three-dimensional region surrounding the flying helicopter, using the ANSYS FLUENT code. The approach is truly three-dimensional, with truly modelled geometry and kinematics of main and tail rotor blades. This applies to modelling of blade flapping and lead-lag motion, too. The trimming procedure uses six independent parameters (i.e. collective and cyclic pitch of main rotor blades, collective pitch of tail rotor blades, pitch, and bank angles of a helicopter) that should be adjusted so as to balance all forces and moments acting on the helicopter. The detailed description of the developed methodology as well as the results of simulation of trimmed hover of the helicopter was presented.

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14

Luo, Bo, Wuli Chu, Song Yan, Zhengjing Shen, and Haoguang Zhang. "Assessment of improved delayed detached eddy simulation in predicting unsteady flows and sound around a circular cylinder." Modern Physics Letters B 35, no. 23 (July 8, 2021): 2150384. http://dx.doi.org/10.1142/s021798492150384x.

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Unsteady flows in the field of engineering are usually calculated by the Unsteady Reynolds-Averaged Navier–Stokes (URANS) owing to the low requirements for computational efforts. However, the numerical resolution of URANS, especially in predicting the unsteady wake flows and sound, is still questionable. In this work, unsteady flow and sound calculations of a circular cylinder are carried out using Improved Delayed Detached Eddy Simulation (IDDES) and the Ffowcs Williams–Hawkings (FW-H) analogy. The predicted results of this calculation are compared with those from the previous studies in the literature in terms of the mean and RMS of the velocity components as well as the sound pressure. The results show that IDDES retains much of the numerical accuracy of the Large Eddy Simulation (LES) approach in predicting unsteady flows and noise while requiring a reduced computational resources in comparison to LES. It is believed that the IDDES can be applied to calculate the complex unsteady flows and flow generated sound with reasonable accuracy in engineering field, which can be used as a promising method for scale-resolving simulations to avoid the expensive computational requirements of LES.

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15

Nayyar, P., G. N. Barakos, and K. J. Badcock. "Numerical study of transonic cavity flows using large-eddy and detached-eddy simulation." Aeronautical Journal 111, no. 1117 (March 2007): 153–64. http://dx.doi.org/10.1017/s0001924000004413.

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Numerical analysis of the flow in weapon bays modelled as open rectangular cavities of length-to-depth (L/D) ratio of 5 and width-to-depth (W/D) ratio of 1 with doors-on and doors-off is presented. Flow conditions correspond to Mach and Reynolds numbers (based on cavity length) of 0·85 and 6·783m respectively. Results from unsteady Reynolds-averaged Navier-Stokes (URANS), large-eddy simulation (LES) and detached-eddy simulation (DES) are compared with the simulation methods demonstrating the best prediction of this complex flow. It was found that URANS was not able to predict the change of flow characteristics between the doors-on and doors-off configurations. In addition, the energy content of the cavity flow modes was much better resolved with DES and LES. Further, the DES was found to be quite capable for this problem giving accurate results (within 3dB of) experiments and appears to be a promising alternative to LES for modelling massively separated flows.

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Viswanathan, Aroon K., and Danesh K. Tafti. "A Comparative Study of DES and URANS for Flow Prediction in a Two-Pass Internal Cooling Duct." Journal of Fluids Engineering 128, no. 6 (April 14, 2006): 1336–45. http://dx.doi.org/10.1115/1.2353279.

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The capabilities of the detached eddy simulation (DES) and the unsteady Reynolds averaged Navier-Stokes (URANS) versions of the 1988 k-ω model in predicting the turbulent flow field in a two-pass internal cooling duct with normal ribs is presented. The flow is dominated by the separation and reattachment of shear layers; unsteady vorticity induced secondary flows and strong streamline curvature. The techniques are evaluated in predicting the developing flow at the entrance to the duct and downstream of the 180deg bend, fully developed regime in the first pass, and in the 180deg bend. Results of mean flow quantities, secondary flows, and the average friction factor are compared to experiments and large-eddy simulations (LES). DES predicts a slower flow development than LES, whereas URANS predicts it much earlier than LES computations and experiments. However, it is observed that as fully developed conditions are established, the capability of the base model in predicting the flow is enhanced by the DES formulation. DES accurately predicts the flow both in the fully developed region as well as the 180deg bend of the duct. URANS fails to predict the secondary flows in the fully developed region of the duct and is clearly inferior to DES in the 180deg bend.

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de Laborderie, Jerome, Laurent Soulat, and Stephane Moreau. "Prediction of Noise Sources in Axial Compressor from URANS Simulation." Journal of Propulsion and Power 30, no. 5 (September 2014): 1257–71. http://dx.doi.org/10.2514/1.b35000.

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Kocutar, P., L. Škerget, and J. Ravnik. "Hybrid LES/URANS simulation of turbulent natural convection by BEM." Engineering Analysis with Boundary Elements 61 (December 2015): 16–26. http://dx.doi.org/10.1016/j.enganabound.2015.06.005.

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Sadiki, A., A. Maltsev, B. Wegner, F. Flemming, A. Kempf, and J. Janicka. "Unsteady methods (URANS and LES) for simulation of combustion systems." International Journal of Thermal Sciences 45, no. 8 (August 2006): 760–73. http://dx.doi.org/10.1016/j.ijthermalsci.2005.11.001.

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20

Münsterjohann, Sven, Jens Grabinger, Stefan Becker, and Manfred Kaltenbacher. "CAA of an Air-Cooling System for Electronic Devices." Advances in Acoustics and Vibration 2016 (October 20, 2016): 1–17. http://dx.doi.org/10.1155/2016/4785389.

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This paper presents the workflow and the results of fluid dynamics and aeroacoustic simulations for an air-cooling system as used in electronic devices. The setup represents a generic electronic device with several electronic assemblies with forced convection cooling by two axial fans. The aeroacoustic performance is computed using a hybrid method. In a first step, two unsteady CFD simulations using the Unsteady Reynolds-Averaged Navier-Stokes simulation with Shear Stress Transport (URANS-SST) turbulence model and the Scale Adaptive Simulation with Shear Stress Transport (SAS-SST) models were performed. Based on the unsteady flow results, the acoustic source terms were calculated using Lighthill’s acoustic analogy. Propagation of the flow-induced sound was computed using the Finite Element Method. Finally, the results of the acoustic simulation are compared with measurements and show good agreement.

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Stalewski, Wienczyslaw, and Katarzyna Surmacz. "Investigations of the vortex ring state on a helicopter main rotor using the URANS solver." Aircraft Engineering and Aerospace Technology 92, no. 9 (April 10, 2020): 1327–37. http://dx.doi.org/10.1108/aeat-12-2019-0264.

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Purpose This paper aims to present the novel methodology of computational simulation of a helicopter flight, developed especially to investigate the vortex ring state (VRS) – a dangerous phenomenon that may occur in helicopter vertical or steep descent. Therefore, the methodology has to enable modelling of fast manoeuvres of a helicopter such as the entrance in and safe escape from the VRS. The additional purpose of the paper is to discuss the results of conducted simulations of such manoeuvres. Design/methodology/approach The developed methodology joins several methods of computational fluid dynamics and flight dynamic. The approach consists of calculation of aerodynamic forces acting on rotorcraft, by solution of the unsteady Reynold-averaged Navier–Stokes (URANS) equations using the finite volume method. In parallel, the equations of motion of the helicopter and the fluid–structure-interaction equations are solved. To reduce computational costs, the flow effects caused by rotating blades are modelled using a simplified approach based on the virtual blade model. Findings The developed methodology of computational simulation of fast manoeuvres of a helicopter may be a valuable and reliable tool, useful when investigating the VRS. The presented results of conducted simulations of helicopter manoeuvres qualitatively comply with both the results of known experimental studies and flight tests. Research limitations/implications The continuation of the presented research will primarily include quantitative validation of the developed methodology, with respect to well-documented flight tests of real helicopters. Practical implications The VRS is a very dangerous phenomenon that usually causes a sudden decrease of rotor thrust, an increase of the descent rate, deterioration of manoeuvrability and deficit of power. Because of this, it is difficult and risky to test the VRS during the real flight tests. Therefore, the reliable computer simulations performed using the developed methodology can significantly contribute to increase helicopter flight safety. Originality/value The paper presents the innovative and original methodology for simulating fast helicopter manoeuvres, distinguished by the original approach to flight control as well as the fact that the aerodynamic forces acting on the rotorcraft are calculated during the simulation based on the solution of URANS equations.

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Sagimbayev, Sagi, Yestay Kylyshbek, Sagidolla Batay, Yong Zhao, Sai Fok, and Teh Soo Lee. "3D Multidisciplinary Automated Design Optimization Toolbox for Wind Turbine Blades." Processes 9, no. 4 (March 26, 2021): 581. http://dx.doi.org/10.3390/pr9040581.

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This paper presents two novel automated optimization approaches. The first one proposes a framework to optimize wind turbine blades by integrating multidisciplinary 3D parametric modeling, a physics-based optimization scheme, the Inverse Blade Element Momentum (IBEM) method, and 3D Reynolds-averaged Navier–Stokes (RANS) simulation; the second method introduces a framework combining 3D parametric modeling and an integrated goal-driven optimization together with a 4D Unsteady Reynolds-averaged Navier–Stokes (URANS) solver. In the first approach, the optimization toolbox operates concurrently with the other software packages through scripts. The automated optimization process modifies the parametric model of the blade by decreasing the twist angle and increasing the local angle of attack (AoA) across the blade at locations with lower than maximum 3D lift/drag ratio until a maximum mean lift/drag ratio for the whole blade is found. This process exploits the 3D stall delay, which is often ignored in the regular 2D BEM approach. The second approach focuses on the shape optimization of individual cross-sections where the shape near the trailing edge is adjusted to achieve high power output, using a goal-driven optimization toolbox verified by 4D URANS Computational Fluid Dynamics (CFD) simulation for the whole rotor. The results obtained from the case study indicate that (1) the 4D URANS whole rotor simulation in the second approach generates more accurate results than the 3D RANS single blade simulation with periodic boundary conditions; (2) the second approach of the framework can automatically produce the blade geometry that satisfies the optimization objective, while the first approach is less desirable as the 3D stall delay is not prominent enough to be fruitfully exploited for this particular case study.

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Richardson, G. A., W. N. Dawes, and A. M. Savill. "An unsteady, moving mesh CFD simulation for Harrier hot-gas ingestion control analysis." Aeronautical Journal 111, no. 1117 (March 2007): 133–44. http://dx.doi.org/10.1017/s0001924000004395.

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Hot gas ingestion (HGI) can be a problematic feature of short take-off vertical landing (STOVL) aircraft during the descent phase of landing, or while on the ground. The hot exhaust gases from the downwards pointing nozzles can be re-ingested into the engine intakes, causing power degradation or reduced engine surge margin. The flow-fields that characterise this phenomenon are complex, with supersonic impinging jets and cross-flows creating large ground vortices and fountain up-wash flows. A flow solver has been developed to include a suitable linear mesh deformation technique for the descending aircraft configuration. The code has been applied to predict the occurrence of HGI, by simulating experimental results from a 1/15th scale model of a descending Harrier. This has enabled an understanding of the aerodynamic mechanisms that govern HGI, in terms of the near-field and far-field effects and their impact on the magnitude of temperatures at the engine intake. This paper presents three sets of CFD results. First a validation exercise shows predicted results from the twin-jet with intake in crossflow test-case. This is an unsteady Reynolds averaged Navier Stokes (URANS) solution for a static geometry (there is no moving mesh). This allows comparison with experiment. Secondly, a full descent phase URANS Spalart-Allmaras (SA) turbulence model calculation is done on an 8·5m cell mesh for half the flow domain of the Harrier model and test-rig without dams/strakes. This shows how the HGI flow mechanisms affect the engine intake temperature profiles, for the case where there are no flow control methods on the underside of the aircraft. Thirdly, the full descent phase URANS SA turbulence model calculation is done on a 22·4m cell mesh for the full flow domain of the Harrier model and test-rig, with the dam/strake geometry included in the structured mesh region.

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Stalewski, Wieńczysław, and Katarzyna Surmacz. "Helicopter Flight Simulation based on URANS Solver and Virtual Blade Model." Journal of KONES 26, no. 3 (September 1, 2019): 211–17. http://dx.doi.org/10.2478/kones-2019-0075.

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Abstract The methodology of simulation of a rotorcraft flight has been developed and applied to simulate several stages of flight of light helicopter. The methodology is based on coupling of several computational models of Computational Fluid Dynamics, Flight Dynamic. The essence of the methodology consists in calculation of aerodynamic forces acting on the flying rotorcraft by solving during the simulation the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. In this approach, the rotorcraft is flying inside the computational 3D mesh modelling the space filled with the air. The flight simulation procedure is completely embedded in the URANS solver ANSYS FLUENT. Flow effects caused by rotating blades of main or tail rotor are modelled by application of the developed Virtual Blade Model (VBM). In this approach, real rotors are replaced by volume discs influencing the flow field similarly as rotating blades. Time-averaged aerodynamic effects of rotating blades are modelled using momentum source terms placed inside the volume-disc zones. The momentum sources are evaluated based on the Blade Element Theory, which associates local flow parameters in the blade sections with databases of 2D-aerodynamic characteristics of these sections. Apart of the VBM module, two additional UDF modules support the simulation of helicopter flight: the module responsible for modelling of all kinematic aspects of the flight and the module gathering the momentary aerodynamic loads and solves 6 DOF-Equations describing a motion of the helicopter seen as solid body. Exemplary simulation of helicopter flight, starting from a hover, through an acceleration and fast flight until a deceleration and steep descent, has been discussed.

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Huijnen, V., L. M. T. Somers, R. S. G. Baert, L. P. H. de Goey, C. Olbricht, A. Sadiki, and J. Janicka. "Study of Turbulent Flow Structures of a Practical Steady Engine Head Flow Using Large-Eddy Simulations." Journal of Fluids Engineering 128, no. 6 (April 21, 2006): 1181–91. http://dx.doi.org/10.1115/1.2353259.

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The prediction performance of two computational fluid dynamics codes is compared to each other and to experimental data of a complex swirling and tumbling flow in a practical complex configuration. This configuration consists of a flow in a production-type heavy-duty diesel engine head with 130-mm cylinder bore. One unsteady Reynolds-averaged Navier-Stokes (URANS)-based simulation and two large-eddy simulations (LES) with different inflow conditions have been performed with the KIVA-3V code. Two LES with different resolutions have been performed with the FASTEST-3D code. The parallelization of the this code allows for a more resolved mesh compared to the KIVA-3V code. This kind of simulations gives a complete image of the phenomena that occur in such configurations, and therefore represents a valuable contribution to experimental data. The complex flow structures gives rise to an inhomogeneous turbulence distribution. Such inhomogeneous behavior of the turbulence is well captured by the LES, but naturally damped by the URANS simulation. In the LES, it is confirmed that the inflow conditions play a decisive role for all main flow features. When no particular treatment of the flow through the runners can be made, the best results are achieved by computing a large part of the upstream region, once performed with the FASTEST-3D code. If the inflow conditions are tuned, all main complex flow structures are also recovered by KIVA-3V. The application of upwinding schemes in both codes is in this respect not crucial.

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Mejia, Omar, Jhon Quiñones, and Santiago Laín. "RANS and Hybrid RANS-LES Simulations of an H-Type Darrieus Vertical Axis Water Turbine." Energies 11, no. 9 (September 6, 2018): 2348. http://dx.doi.org/10.3390/en11092348.

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Nowadays, the global energy crisis has encouraged the use of alternative sources like the energy available in the water currents of seas and rivers. The vertical axis water turbine (VAWT) is an interesting option to harness this energy due to its advantages of facile installation, maintenance and operation. However, it is known that its efficiency is lower than that of other types of turbines due to the unsteady effects present in its flow physics. This work aims to analyse through Computational Fluid Dynamics (CFD) the turbulent flow dynamics around a small scale VAWT confined in a hydrodynamic tunnel. The simulations were developed using the Unsteady Reynolds Averaged Navier Stokes (URANS), Detached Eddy Simulation (DES) and Delayed Detached Eddy Simulation (DDES) turbulence models, all of them based on k-ω Shear Stress Transport (SST). The results and analysis of the simulations are presented, illustrating the influence of the tip speed ratio. The numerical results of the URANS model show a similar behaviour with respect to the experimental power curve of the turbine using a lower number of elements than those used in the DES and DDES models. Finally, with the help of both the Q-criterion and field contours it is observed that the refinements made in the mesh adaptation process for the DES and DDES models improve the identification of the scales of the vorticity structures and the flow phenomena present on the near and far wake of the turbine.

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Zhang, Yang, Laiping Zhang, Xin He, Xiaogang Deng, and Haisheng Sun. "Detached Eddy Simulation of Complex Separation Flows Over a Modern Fighter Model at High Angle of Attack." Communications in Computational Physics 22, no. 5 (October 31, 2017): 1309–32. http://dx.doi.org/10.4208/cicp.oa-2016-0132.

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AbstractThis paper presents the simulation of complex separation flows over a modern fighter model at high angle of attack by using an unstructured/hybrid grid based Detached Eddy Simulation (DES) solver with an adaptive dissipation second-order hybrid scheme. Simulation results, including the complex vortex structures, as well as vortex breakdown phenomenon and the overall aerodynamic performance, are analyzed and compared with experimental data and unsteady Reynolds-Averaged Navier-Stokes (URANS) results, which indicates that with the DES solver, clearer vortical flow structures are captured and more accurate aerodynamic coefficients are obtained. The unsteady properties of DES flow field are investigated in detail by correlation coefficient analysis, power spectral density (PSD) analysis and proper orthogonal decomposition (POD) analysis, which indicates that the spiral motion of the primary vortex on the leeward side of the aircraft model is highly nonlinear and dominates the flow field. Through the comparisons of flow topology and pressure distributions with URANS results, the reason why higher and more accurate lift can be obtained by DES is discussed. Overall, these results show the potential capability of present DES solver in industrial applications.

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Yuan, W., M. Khalid, J. Windte, U. Scholz, and R. Radespiel. "Computational and experimental investigations of low-Reynolds-number flows past an aerofoil." Aeronautical Journal 111, no. 1115 (January 2007): 17–29. http://dx.doi.org/10.1017/s000192400000172x.

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AbstractThis paper presents investigations of low-Reynolds-number flows past an SD7003 aerofoil at Re = 60k, where transition takes place across a laminar separation bubble (LSB). Results of experimental measurements and numerical calculations are analysed and discussed. In particular, reasonably good results were obtained using two different numerical approaches: Large-eddy simulation (LES) that demonstrated vortical structures at different transition stages, and where the transition occurred naturally; unsteady Reynolds-averaged Navier-Stokes (URANS) simulations for several turbulence models based on the ω-length-scale equation, coupled to a linear stability solver to predict the transition position.

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Gosteev, Yu A., A. D. Obukhovskiy, and S. D. Salenko. "Numerical simulation of the transverse flow over spans of girder bridges." Advanced Engineering Research 18, no. 4 (December 26, 2018): 362–78. http://dx.doi.org/10.23947/1992-5980-2018-18-4-362-378.

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Introduction. The technique of numerical modeling of the transverse flow over span structures of bridges on the basis of the two-dimensional URANS (Unsteady Reynolds-averaged Navier-Stokes) approach used in the modern methods and software packages for computational fluid dynamics is verified. The work objective was debugging and experimental substantiation of this technique with the use of the database on the aerodynamic characteristics of the cross-sections of span structures of girder bridges of standard shapes pre-developed by the authors.Materials and Methods. A numerical simulation of the transverse flow of low-turbulent (smooth) and turbulent air flows around the bridge structures in a range of practically interesting attack angles is carried out. SST k − ω turbulence model was used as the closing one. The technique was preliminarily tested on the check problem for the flow of the rectangular crosssection beams. Calculations were carried out using the licensed ANSYS software.Research Results. The calculated dependences on the attack angle of the aerodynamic coefficients of forces (drag and lift) and the moment of the cross sections of the girder bridges of standard shapes are obtained. These data refer to the span structures at the construction phase (without deck and parapets, without parapets) and operation phase, under the conditions of model smooth and turbulent incoming flow. The latter allows us to outline the boundaries for more weighted estimates of the aerodynamic characteristics of thegirder bridges in a real wind current. The best agreement with the experimental data was obtained from the drag of the cross-section. The magnitude of the lifting force is more sensitive to the presence and extent of the separation regions, so its numerical determination is less accurate. The reproduction of the angle-of-attack effect on the aerodynamic moment of the cross-section is the most challenging for the majority of configurations.Discussion and Conclusions. Comparison of the calculated and experimental data indicates the applicability of the URANS approach to the operational prediction of the aerodynamic characteristics of the single-beam span structures. In the case of multi-beam span structures, where the aerodynamic interference between separate girders plays an important role, the URANS approach must apparently give way to more accurate eddy-resolving methods. The results obtained can be used in the aerodynamic analysis of structures and in practice of the relevant design organizations in the field of transport construction.

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Krastev, Vesselin Krassimirov, Alessandro d’Adamo, Fabio Berni, and Stefano Fontanesi. "Validation of a zonal hybrid URANS/LES turbulence modeling method for multi-cycle engine flow simulation." International Journal of Engine Research 21, no. 4 (June 12, 2019): 632–48. http://dx.doi.org/10.1177/1468087419851905.

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A zonal hybridization of the RNG [Formula: see text]-[Formula: see text] URANS model is proposed for the simulation of turbulent flows in internal combustion engines. The hybrid formulation is able to act as URANS, DES or LES in different zones of the computational domain, which are explicitly set by the user. The resulting model has been implemented in a commercial computational fluid dynamics code and the LES branch of the modified RNG [Formula: see text]-[Formula: see text] closure has been initially calibrated on a standard homogeneous turbulence box case. Subsequently, the full zonal formulation has been tested on a fixed intake valve geometry, including comparisons with third-party experimental data. The core of the work is represented by a multi-cycle analysis of the TCC-III experimental engine configuration, which has been compared with the experiments and with prior full-LES computational studies. The applicability of the hybrid turbulence model to internal combustion engine flows is demonstrated, and PIV-like flow statistics quantitatively validate the model performance. This study shows a pioneering application of zonal hybrid models in engine-relevant simulation campaigns, emphasizing the relevance of hybrid models for turbulent engine flows.

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D., AMMOUR, ADJLOUT L., ADDAD Y., and REVELL A. "NUMERICAL SIMULATION OF AN IN-LINE TUBE BUNDLE USING THE URANS APPROACH." International Conference on Applied Mechanics and Mechanical Engineering 13, no. 13 (May 1, 2008): 416–30. http://dx.doi.org/10.21608/amme.2008.39755.

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Kocutar, Primož, Jure Ravnik, and Leopold Škerget. "Hybrid LES/URANS Simulation Of Rayleigh-B閚ard Convection Using BEM." Computer Modeling in Engineering & Sciences 123, no. 1 (2020): 1–22. http://dx.doi.org/10.32604/cmes.2020.08728.

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Ramírez, Juan A., and Cristóbal Cortés. "Comparison of Different URANS Schemes for the Simulation of Complex Swirling Flows." Numerical Heat Transfer, Part B: Fundamentals 58, no. 2 (September 30, 2010): 98–120. http://dx.doi.org/10.1080/10407790.2010.508440.

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Lee, Sungwook, and Kwang-Jun Paik. "URANS SIMULATION OF A PARTIALLY SUBMERGED PROPELLER OPERATING UNDER THE BOLLARD CONDITION." Brodogradnja 69, no. 1 (October 1, 2017): 107–21. http://dx.doi.org/10.21278/brod69107.

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Kratzsch, Christoph, Klaus Timmel, Sven Eckert, and Rüdiger Schwarze. "URANS Simulation of Continuous Casting Mold Flow: Assessment of Revised Turbulence Models." steel research international 86, no. 4 (April 2015): 400–410. http://dx.doi.org/10.1002/srin.201400097.

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Hasse, Christian, Volker Sohm, Martin Wetzel, and Bodo Durst. "Hybrid URANS/LES Turbulence Simulation of Vortex Shedding Behind a Triangular Flameholder." Flow, Turbulence and Combustion 83, no. 1 (November 14, 2008): 1–20. http://dx.doi.org/10.1007/s10494-008-9186-7.

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Hu, Y., H. L. Zhang, and C. Tan. "The effect of the aerofoil thickness on the performance of the MAV scale cycloidal rotor." Aeronautical Journal 119, no. 1213 (March 2015): 343–64. http://dx.doi.org/10.1017/s0001924000010502.

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AbstractThe numerical simulations for cycloidal propellers based on five aerofoils with different thickness are presented in this paper. The CFD simulation is based on sliding mesh and URANS. The results of CFD simulation indicates that all test cases share similar flow pattern. There are leading edge vortex and trailing-edge vortex due to blade dynamic stall. Interaction between the vortices shed from upstream blade and the downstream blade can be observed. There is variation of blade relative inflow velocity due to downwash in the cycloidal rotor cage. These factors result in large fluctuations of the aerodynamics forces on the blade. The comparison of the forces and flow pattern indicates that the thickness and leading edge radius of the aerofoil can significantly influent the flow pattern and hence the performance of the cycloidal propeller.

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Decaix, Jean, Vlad Hasmatuchi, Maximilian Titzschkau, and Cécile Münch-Alligné. "CFD Investigation of a High Head Francis Turbine at Speed No-Load Using Advanced URANS Models." Applied Sciences 8, no. 12 (December 5, 2018): 2505. http://dx.doi.org/10.3390/app8122505.

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Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by, and shut-down procedures, which reduces the lifespan of the machines. CFD based on standard URANS turbulence modeling is currently able to predict accurately the performances of the hydraulic turbines for operating points close to the Best Efficiency Point (BEP). However, far from the BEP, the standard URANS approach is less efficient to capture the dynamics of 3D flows. The current study focuses on a hydraulic turbine, which has been investigated at the BEP and at the Speed-No-Load (SNL) operating conditions. Several “advanced” URANS models such as the Scale-Adaptive Simulation (SAS) SST k - ω and the BSL- EARSM have been considered and compared with the SST k - ω model. The main conclusion of this study is that, at the SNL operating condition, the prediction of the topology and the dynamics of the flow on the suction side of the runner blade channels close to the trailing edge are influenced by the turbulence model.

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Ge, Liang, Hwa-Liang Leo, Fotis Sotiropoulos, and Ajit P. Yoganathan. "Flow in a Mechanical Bileaflet Heart Valve at Laminar and Near-Peak Systole Flow Rates: CFD Simulations and Experiments." Journal of Biomechanical Engineering 127, no. 5 (March 31, 2005): 782–97. http://dx.doi.org/10.1115/1.1993665.

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Time-accurate, fully 3D numerical simulations and particle image velocity laboratory experiments are carried out for flow through a fully open bileaflet mechanical heart valve under steady (nonpulsatile) inflow conditions. Flows at two different Reynolds numbers, one in the laminar regime and the other turbulent (near-peak systole flow rate), are investigated. A direct numerical simulation is carried out for the laminar flow case while the turbulent flow is investigated with two different unsteady statistical turbulence modeling approaches, unsteady Reynolds-averaged Navier-Stokes (URANS) and detached-eddy simulation (DES) approach. For both the laminar and turbulent cases the computed mean velocity profiles are in good overall agreement with the measurements. For the turbulent simulations, however, the comparisons with the measurements demonstrate clearly the superiority of the DES approach and underscore its potential as a powerful modeling tool of cardiovascular flows at physiological conditions. The study reveals numerous previously unknown features of the flow.

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Krastev, V. K., G. Di Ilio, G. Falcucci, and G. Bella. "Notes on the hybrid URANS/LES turbulence modeling for Internal Combustion Engines simulation." Energy Procedia 148 (August 2018): 1098–104. http://dx.doi.org/10.1016/j.egypro.2018.08.047.

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Gonçalves Noleto, Luciano, Jhon Nero Vaz Goulart, Manuel Nascimento Dias Barcelos Júnior, and Antonio C. P. Brasil Junior. "A Numerical Study of the Turbulent Flow over a Cylinder close to Moving Plane." Applied Mechanics and Materials 394 (September 2013): 115–20. http://dx.doi.org/10.4028/www.scientific.net/amm.394.115.

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Two-dimensional numerical simulations are performed to analyze the turbulent flow over a circular cylinder close to a moving plane. This flow receives interference from the plane boundary layer, being this effect identified by recirculation zones close to the wall and slight difference in pressure distribution around cylinder. URANS equations and SST modeling are employed to calculate velocity and pressure field. The simulation was performed by a finite element projection scheme. Four distances between the cylinder and the plane are analyzed by the SST model. The SST results showed the generation and development of vortex shedding. Lift and drag coefficients show the flow oscillatory pattern. All results are similar with other numerical results at the literature.

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42

Matias, Ian Jay T., Louis Angelo M. Danao, and Binoe E. Abuan. "Numerical Investigation on the Effects of Varying the Arc length of a Windshield on the Performance of a Highway Installed Banki Wind Turbine." Fluids 6, no. 8 (August 16, 2021): 285. http://dx.doi.org/10.3390/fluids6080285.

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Two-dimensional computational fluid dynamics (CFD) simulations are employed to investigate the effects of adding a circular-arc-shaped windshield on the performance of a Banki type vertical axis wind turbine (VAWT), particularly to the application where the VAWT is harnessing wind energy in highway caused by the passing vehicles. Unsteady Reynolds-Averaged Navier-Stokes (URANS) is the computational approach used to calculate the turbulent flow within the domain. Two sets of simulation cases based on two different vehicles (i.e., car and a bus) are performed with varying arc-length of the windshield. The results show that the windshield provides an increase in the energy captured by the VAWT by up to 16.14% compared to no windshield case when the car model is used. In contrast, windshield in all the simulation cases using a bus model gives a negative effect to VAWT performance where the worst case yields −64.77%.

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Bazdidi-Tehrani, Farzad, and Mehdi Jahromi. "ANALYSIS OF SYNTHETIC JET FLOW FIELD: APPLICATION OF URANS APPROACH." Transactions of the Canadian Society for Mechanical Engineering 35, no. 3 (September 2011): 337–53. http://dx.doi.org/10.1139/tcsme-2011-0019.

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The present paper reports the time dependent simulation of a turbulent plane synthetic jet using an unsteady Reynolds averaged Navier-Stokes approach on the basis of the first and second moment closure turbulence models. All the applied turbulence models can capture a global feature of the long time averaged flow field quite well. However, the standard k – ε model yields a disappointing prediction of the turbulence field with inaccurately high levels of turbulence kinetic energy and normal Reynolds stress distributions. The second moment closure model with quadratic nonlinear pressure strain approximation shows the most reasonable prediction of the phase averaged flow and turbulence fields.

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Zbavitel, Jan, and Simona Fialová. "A numerical study of hemodynamic effects on the bileaflet mechanical heart valve." EPJ Web of Conferences 213 (2019): 02103. http://dx.doi.org/10.1051/epjconf/201921302103.

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The work is focused on calculating hemodynamically negative effects of a flow through bileaflet mechanical heart valves (BMHV). Open-source FOAM-extend and cfMesh libraries were used for numerical simulation, the leaflet movement was solved as a fluid-structure interaction. A real model of the Sorin Bicarbon heart valve was employed as the default geometry for the following shape improvement. The unsteady boundary conditions correspond to physiological data of a cardiac cycle. It is shown how the modification of the shape of the original valve geometry positively affected the size of backflow areas. Based on numerical results, a significant reduction of shear stress magnitude is shown. The outcome of a direct numerical simulation (DNS) of transient flow was compared with results of low-Reynolds URANS model k-ω SST. Despite the limits of the two-dimensional solution and Newtonian fluid model, the suitability of models frequently used in literature was reviewed. Use of URANS models can suppress the formation of some relevant vortex structures which may affect the BMHV’s dynamics. The results of this analysis can find use in optimizing the design of the mechanical valve that would cause less damage to the blood cells and lower risk of thrombus formation.

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Xiao, Yizhou, Wenxin Huai, Bin Ji, and Zhonghua Yang. "Verification and Validation of URANS Simulations of the Round Buoyant Jet in Counterflow." Water 10, no. 11 (October 24, 2018): 1509. http://dx.doi.org/10.3390/w10111509.

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This paper presents a study on the verification and validation (V&V) of numerical solutions for round buoyant jets in counterflow. The unsteady flow was simulated using an unsteady Reynolds-averaged Navier–Stokes (URANS) solver with a two-phase mixture model. This work aimed to quantitatively investigate the reliability and applicability of various uncertainty estimators in the simulation of a buoyant jet in counterflow. Analysis of the discretization uncertainty estimation results revealed that the factor of safety (FS) and the modified FS (FS1) methods were the appropriate evaluation estimators in the simulation of a buoyant jet in counterflow. Validation by comparison with the experimental data indicated that the area without achieving the validation at the validation level was strongly related to the shear layer between the jet flow and the ambient fluid. Moreover, the predicted concentration contours, coherent structures, and centerline concentration were strongly affected by the grid resolution.

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Shen, Zhi-rong, Hai-xuan Ye, and De-cheng Wan. "URANS simulations of ship motion responses in long-crest irregular waves." Journal of Hydrodynamics 26, no. 3 (June 2014): 436–46. http://dx.doi.org/10.1016/s1001-6058(14)60050-0.

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Kornev, N., A. Taranov, E. Shchukin, and L. Kleinsorge. "Development of hybrid URANS–LES methods for flow simulation in the ship stern area." Ocean Engineering 38, no. 16 (November 2011): 1831–38. http://dx.doi.org/10.1016/j.oceaneng.2011.09.024.

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Nouroozi, Hossein, and Hamid Zeraatgar. "A reliable simulation for hydrodynamic performance prediction of surface-piercing propellers using URANS method." Applied Ocean Research 92 (November 2019): 101939. http://dx.doi.org/10.1016/j.apor.2019.101939.

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Bhushan, Shanti, Tao Xing, Pablo Carrica, and Frederick Stern. "Model-and Full-Scale URANS Simulations of Athena Resistance, Powering, Seakeeping, and 5415 Maneuvering." Journal of Ship Research 53, no. 04 (December 1, 2009): 179–98. http://dx.doi.org/10.5957/jsr.2009.53.4.179.

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This study demonstrates the versatility of a two-point, multilayer wall function in computing model-and full-scale ship flows with wall roughness and pressure gradient effects. The wall-function model is validated for smooth flat-plate flows at Reynolds numbers up to 109, and it is applied to the Athena R/V for resistance, propulsion, and seakeeping calculations and to fully appended DTMB 5415 for a maneuvering simulation. Resistance predictions for Athena bare hull with skeg at the model scale compare well with the near-wall turbulence model results and experimental fluid dynamics (EFD) data. For full-scale simulations, frictional resistance coefficient predictions using smooth wall are in good agreement with the International Towing Tank Conference (ITTC) line. Rough-wall simulations show higher frictional and total resistance coefficients, where the former is found to be in good agreement with the ITTC correlation allowance. Self-propelled simulations for the fully appended Athena performed at full scale using rough-wall conditions compare well with full-scale data extrapolated from model-scale measurements using the ITTC ship-model correlation line including a correlation allowance. Full-scale computations are performed for the towed fully appended Athena free to sink and trim and the boundary layer and wake profiles are compared with full-scale EFD data. Rough-wall results are found to be in better agree-ment with the EFD data than the smooth-wall results. Seakeeping calculations are performed for the demonstration purpose at both model-and full-scale. Maneuvering calculation shows slightly more efficient rudder action, lower heading angle overshoots, and lower roll damping for full-scale than shown by the model scale.

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Wenig, Philipp J., Ruiyun Ji, Stephan Kelm, and Markus Klein. "Towards Uncertainty Quantification of LES and URANS for the Buoyancy-Driven Mixing Process between Two Miscible Fluids—Differentially Heated Cavity of Aspect Ratio 4." Fluids 6, no. 4 (April 17, 2021): 161. http://dx.doi.org/10.3390/fluids6040161.

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Numerical simulations are subject to uncertainties due to the imprecise knowledge of physical properties, model parameters, as well as initial and boundary conditions. The assessment of these uncertainties is required for some applications. In the field of Computational Fluid Dynamics (CFD), the reliable prediction of hydrogen distribution and pressure build-up in nuclear reactor containment after a severe reactor accident is a representative application where the assessment of these uncertainties is of essential importance. The inital and boundary conditions that significantly influence the present buoyancy-driven flow are subject to uncertainties. Therefore, the aim is to investigate the propagation of uncertainties in input parameters to the results variables. As a basis for the examination of a representative reactor test containment, the investigations are initially carried out using the Differentially Heated Cavity (DHC) of aspect ratio 4 with Ra=2×109 as a test case from the literature. This allows for gradual method development for guidelines to quantify the uncertainty of natural convection flows in large-scale industrial applications. A dual approach is applied, in which Large Eddy Simulation (LES) is used as reference for the Unsteady Reynolds-Averaged Navier–Stokes (URANS) computations. A methodology for the uncertainty quantification in engineering applications with a preceding mesh convergence study and sensitivity analysis is presented. By taking the LES as a reference, the results indicate that URANS is able to predict the underlying mixing process at Ra=2×109 and the variability of the result variables due to parameter uncertainties.

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Journal articles on the topic 'Simulation URANS'

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