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Статті в журналах з теми "RANS numerical simulation"

Автор: Grafiati

Опубліковано: 16 вересня 2022

Оновлено: 19 липня 2025

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Zhang, Shu Jia, Yue Ping Tong, and Le Hu. "Examine Applicability of the RANS and LES Method on Numerical Simulation of Centrifugal Pump." Applied Mechanics and Materials 55-57 (May 2011): 582–86. http://dx.doi.org/10.4028/www.scientific.net/amm.55-57.582.

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In order to examine applicability of the Reynolds-Averaged Navier-Stokes （RANS）using Reynolds Stress equation Model (RSM) and the Large Eddy Simulation (LES) in numerical simulation of centrifugal pump, a series of 3D numerical simulation at the design point and at six off-design points were carried out with the two methods. The object is based on IS80-65-160 centrifugal pump. According to the results obtained, head, shaft power, efficiency of pump were calculated, the simulated performance curves of a centrifugal pump is processed. The simulated performance curves of a centrifugal pump were compared with the experimental performance curves. It was confirmed that RANS were suitable for the numerical simulation of the internal flow inside a centrifugal pump. But the result of LES is not very good if the same gambit which is suitable for RANS was used. Therefore, the computer resources, not propose the Large Eddy Simulation (LES) method in numerical simulations of centrifugal pump.

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Grecu, I. S., G. Dunca, D. M. Bucur, and M. J. Cervantes. "URANS numerical simulations of pulsating flows considering streamwise pressure gradient on asymmetric diffuser." IOP Conference Series: Earth and Environmental Science 1079, no. 1 (2022): 012087. http://dx.doi.org/10.1088/1755-1315/1079/1/012087.

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Abstract The paper focuses on implementing the wall model developed by Manhart, in Reynolds Averaged Navier - Stokes (RANS) turbulence models used in the field of Computational Fluid Dynamics (CFD). This wall model considers the influence of the streamwise pressure gradient in addition to the existing wall models used in the usual CFD codes. In the present work, two RANS numerical simulations are carried out using the k-ω Shear Stress Transport (SST) turbulence model on an asymmetric diffuser geometry. One numerical simulation is carried out using the implementation of the Manhart wall model in the k-ω SST turbulence model, and the other numerical simulation is performed using the standard formulation of the k-ω SST turbulence model. The numerical simulations carried out using the Manhart wall model and the standard formulation of the k-ω SST are compared with experimental measurements made on the asymmetric diffuser experimental installation. The numerical simulations are carried out using a free, open-source CFD tool, Code_Saturne. The comparisons between numerical simulations and the experimental data are in good agreement in the boundary layer of the flow inside the diffuser. The Manhart wall model had a faster convergence resulting in a shorter simulation time.

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Ketong, Liu, and Tang Aiping. "Numerical Investigation for Aerodynamic Derivatives of Bridge Deck Using DES." Open Civil Engineering Journal 8, no. 1 (2014): 326–34. http://dx.doi.org/10.2174/1874149501408010326.

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Detached Eddy Simulation（DES）is quite a new approach for the treatment of turbulence, which unites the efficiency of Reynolds Averaged Navier-Stokes Simulation (RANS) and the accuracy of Large Eddy Simulation (LES) into one framework. In this paper, DES method based on Spalart-Allmaras (S-A) turbulence model is employed to simulate the incompressible viscous flow around bridge decks. In order to obtain the aerodynamic forces, the forced motion simulations of the bridge decks are implemented by self-developed codes combined with FLUENT software. After obtaining the aerodynamic forces, aerodynamic derivatives are determined based on the least square algorithm. As the examples, the thin flat plate and the Great Belt East Bridge suspended spans cross-section are investigated to calculate their aerodynamic derivatives. Finally, the simulation results are compared to the data reported in other studies. The comparisons show that the present method gives much better prediction of the aerodynamic derivatives than RANS method and discrete vortex method (DVM).

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Baranova, T. A., Yu V. Zhukova, A. D. Chorny, A. N. Skrypnik, R. A. Aksyanov, and I. A. Popov. "Non-isothermal vortex flow in the T-junction channel." Journal of Physics: Conference Series 2088, no. 1 (2021): 012034. http://dx.doi.org/10.1088/1742-6596/2088/1/012034.

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Abstract In this work we present the numerical simulation of coolant mixing modes in the T-junction. We shows that the RANS approach is beneficial for a qualitative flow analysis to obtain relatively agreed averaged velocity and temperature. Moreover, traditionally, the RANS approach calculates only the averaged temperature distribution. It should also be emphasized that unlike the LES approach, the steady RANS approach cannot express a local flow structure in intense mixing zones. Nevertheless, apparently the used RANS approach should be used for assessing the quality of computational grids, boundary conditions in order to use the LES approach for further numerical simulation.

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Hsiao, C. T., and G. L. Chahine. "Numerical Study of Cavitation Inception Due to Vortex/Vortex Interaction in a Ducted Propulsor." Journal of Ship Research 52, no. 02 (2008): 114–23. http://dx.doi.org/10.5957/jsr.2008.52.2.114.

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Cavitation inception in a ducted propulsor was studied numerically using Navier-Stokes computations and bubble dynamics models. Experimental observations of the propulsor model and previous numerical computations using Reynolds-averaged Navier-Stokes (RANS) codes indicated that cavitation inception occurred in the region of interaction of the leakage and trailing tip vortices. The RANS simulations failed, however, to predict correctly both the cavitation inception index value and the inception location. To improve the numerical predictions, we complemented here the RANS computations with a direct Navier-Stokes simulation in a reduced computational domain including the region of interaction of the two vortices. Initial and boundary conditions in the reduced domain were provided by the RANS solution of the full ducted propulsor flow. Bubble nuclei were released in this flow field, and spherical and nonspherical bubble dynamics models were exercised to investigate cavitation inception. This resulted in a solution in much better agreement with the experimental measurements than the original RANS solution. Both the value of the cavitation inception index and the location of the cavitation inception were very well captured. The characteristics of the emitted acoustic signals and of the bubble shapes during a cavitation event were also computed.

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Viti, Nicolò, Daniel Valero, and Carlo Gualtieri. "Numerical Simulation of Hydraulic Jumps. Part 2: Recent Results and Future Outlook." Water 11, no. 1 (2018): 28. http://dx.doi.org/10.3390/w11010028.

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During the past two decades, hydraulic jumps have been investigated using Computational Fluid Dynamics (CFD). The second part of this two-part study is devoted to the state-of-the-art of the numerical simulation of the hydraulic jump. First, the most widely-used CFD approaches, namely the Reynolds-Averaged Navier–Stokes (RANS), the Large Eddy Simulation (LES), the Direct Numerical Simulation (DNS), the hybrid RANS-LES method Detached Eddy Simulation (DES), as well as the Smoothed Particle Hydrodynamics (SPH), are introduced pointing out their main characteristics also in the context of the best practices for CFD modeling of environmental flows. Second, the literature on numerical simulations of the hydraulic jump is presented and discussed. It was observed that the RANS modeling approach is able to provide accurate results for the mean flow variables, while high-fidelity methods, such as LES and DES, can properly reproduce turbulence quantities of the hydraulic jump. Although computationally very expensive, the first DNS on the hydraulic jump led to important findings about the structure of the hydraulic jump and scale effects. Similarly, application of the Lagrangian meshless SPH method provided interesting results, notwithstanding the lower research activity. At the end, despite the promising results still available, it is expected that with the increase in the computational capabilities, the RANS-based numerical studies of the hydraulic jump will approach the prototype scale problems, which are of great relevance for hydraulic engineers, while the application at this scale of the most advanced tools, such as LES and DNS, is still beyond expectations for the foreseeable future. Knowledge of the uncertainty associated with RANS modeling may allow the careful design of new hydraulic structures through the available CFD tools.

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Zhang, Lu, Yongfei Mou, Fan Liu, Shuai Ma, and Xingda Cui. "Grid density effect for numerical simulation of civil aircraft in post stall." Journal of Physics: Conference Series 2599, no. 1 (2023): 012002. http://dx.doi.org/10.1088/1742-6596/2599/1/012002.

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Abstract Stall will deteriorate flight safety and cause serious accidents for civil aircraft. RANS-LES hybrid approaches have become a compromise choice due to insufficient ability of RANS for large flow separation. In present work, Zonal Detached-eddy-simulation coupled with high-order spatial scheme were employed to investigated grid density effect in the numerical simulations. The calculations show that the grid density would affect the numerical simulation of the small-scale flow structure in the wake of region of the main wing, and further affect the disturbance of main wing to the horizontal tail. It is necessary to properly densify the grid downstream of the main wing in order to accurately predict the aircraft stall.

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Eastwood, Simon J., Paul G. Tucker, Hao Xia, and Christian Klostermeier. "Developing large eddy simulation for turbomachinery applications." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, no. 1899 (2009): 2999–3013. http://dx.doi.org/10.1098/rsta.2008.0281.

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For jets, large eddy resolving simulations are compared for a range of numerical schemes with no subgrid scale (SGS) model and for a range of SGS models with the same scheme. There is little variation in results for the different SGS models, and it is shown that, for schemes which tend towards having dissipative elements, the SGS model can be abandoned, giving what can be termed numerical large eddy simulation (NLES). More complex geometries are investigated, including coaxial and chevron nozzle jets. A near-wall Reynolds-averaged Navier–Stokes (RANS) model is used to cover over streak-like structures that cannot be resolved. Compressor and turbine flows are also successfully computed using a similar NLES–RANS strategy. Upstream of the compressor leading edge, the RANS layer is helpful in preventing premature separation. Capturing the correct flow over the turbine is particularly challenging, but nonetheless the RANS layer is helpful. In relation to the SGS model, for the flows considered, evidence suggests issues such as inflow conditions, problem definition and transition are more influential.

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Soni, Rahul Kumar, Nitish Arya, and Ashoke De. "Numerical simulation of supersonic separating-reattaching flow through RANS." Journal of Physics: Conference Series 822 (April 11, 2017): 012037. http://dx.doi.org/10.1088/1742-6596/822/1/012037.

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Baranova, Tatyana A., Yulia V. Zhukova, Andrei D. Chorny, Artem Skrypnik, and Igor A. Popov. "Non-Isothermal Vortex Flow in the T-Junction Pipe." Energies 14, no. 21 (2021): 7002. http://dx.doi.org/10.3390/en14217002.

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The numerical simulation approach of heat carrier mixing regimes in the T-junction shows that the RANS approach is beneficial for a qualitative flow analysis to obtain relatively agreed averaged velocity and temperature. Moreover, traditionally, the RANS approach only predicts the averaged temperature distribution. This mathematical model did not consider the temperature fluctuation variations important for the thermal fatigue task. It should also be emphasized that unlike the LES approach, the steady RANS approach cannot express a local flow structure in intense mixing zones. Nevertheless, apparently the adopted RANS approach should be used for assessing the quality of computational meshes, boundary conditions with the purpose to take LES for further numerical simulation.

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Arfaoui, Ahlem, Catalin Viorel Popa, Redha Taïar, Guillaume Polidori, and Stéphane Fohanno. "Numerical Streamline Patterns at Swimmer’s Surface Using RANS Equations." Journal of Applied Biomechanics 28, no. 3 (2012): 279–83. http://dx.doi.org/10.1123/jab.28.3.279.

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The objective of this article is to perform a numerical modeling on the flow dynamics around a competitive female swimmer during the underwater swimming phase for a velocity of 2.2 m/s corresponding to national swimming levels. Flow around the swimmer is assumed turbulent and simulated with a computational fluid dynamics method based on a volume control approach. The 3D numerical simulations have been carried out with the code ANSYS FLUENT and are presented using the standard k-ω turbulence model for a Reynolds number of 6.4 × 106. To validate the streamline patterns produced by the simulation, experiments were performed in the swimming pools of the National Institute of Sports and Physical Education in Paris (INSEP) by using the tufts method.

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Xue, Xiao, Hua-Dong Yao, and Lars Davidson. "Synthetic turbulence generator for lattice Boltzmann method at the interface between RANS and LES." Physics of Fluids 34, no. 5 (2022): 055118. http://dx.doi.org/10.1063/5.0090641.

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The paper presents a synthetic turbulence generator (STG) for the lattice Boltzmann method (LBM) at the interface of the Reynolds averaged Navier–Stokes (RANS) equations and the LBM large eddy simulation (LES). We first obtain the RANS velocity field from a finite volume solver at the interface. Then, we apply a numerical interpolation from the RANS velocity field to the LBM velocity field due to the different grid types of RANS and LBM. The STG method generates the velocity fluctuations, and the regularized LBM reconstructs the particle distribution functions at the interface. We perform a turbulent channel flow simulation at [Formula: see text] with the STG at the inlet and the pressure-free boundary condition at the outlet. The velocity field is quantitatively compared with the periodic lattice Boltzmann based LES (LES-LBM) channel flow and the direct numerical simulation (DNS) channel flow. Both the adaptation length and time for the STG method are evaluated. Also, we compare the STG-LBM channel flow results with the existing LBM synthetic eddy method (SEM-LBM) results. Our numerical investigations show good agreement with the DNS and periodic LES-LBM channel flow within a short adaptation length. The adaptation time for the turbulent channel flow is quantitatively analyzed and matches the DNS around 1.5–3 domain flow-through time. Finally, we check the auto-correlation for the velocity components at different cross sections of the streamwise direction. The proposed STG-LBM is observed to be both fast and robust. The findings show good potential for the hybrid RANS/LES-LBM based solver on the aerodynamics simulations and a broad spectrum of engineering applications.

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Bounouar, Mokhtari, and Guessab Ahmed. "A Comparative Study between FGM and SLF Approach for Turbulent Piloted Flame of Methane." WSEAS TRANSACTIONS ON FLUID MECHANICS 18 (December 31, 2023): 272–82. http://dx.doi.org/10.37394/232013.2023.18.26.

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This study validates the RANS simulation results by comparing them with experimental data. Numerical simulations were performed for a piloted methane-air jet flame in an axisymmetric burner. It is noteworthy that RANS simulations have been performed using a Non-premixed model with Steady Laminar Flamelet (SLF) and a partially premixed model with Flamelet Generated Manifold (FGM) of the Ansys-Fluent solver are used to express the chemistry-turbulence interaction, to provide an initial solution to the simulation performed by the Pdf transported, joint two kinetic mechanisms for oxidation of methane, detailed GRI-Mech 3.0 mechanism (53 species, 325 reactions), and CH4-Skeletal mechanism (16 species, 41-step). The case test consists of a rich premixed flame (Sandia Flame D). A comparison between the results of the obtained simulations and experimental data shows good agreement, in particular in the context of RANS/FGM with both mechanisms (GRI 3.0 and CH4-Skel).

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Guo, Jiahao, Xiaoping Zhu, Zhou Zhou, and Xiaoping Xu. "Numerical Simulation and Characteristic Analysis of Ship's Air Flow Field." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, no. 6 (2018): 1037–44. http://dx.doi.org/10.1051/jnwpu/20183661037.

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The air flow field of ship was simulated by using computational fluid dynamics technology to analyze its prime characteristics with reasonable accuracy. The different results of Reynolds-Averaged Navier-Stokes (RANS) method and Detached Eddy Simulation (DES) were compared, and the calculation traits of these methods were discussed. The results show that the air flow field of ship is unsteady. The accuracy of RANS simulation is insufficient for capturing this unsteady phenomenon. However, DES can catch this with better accuracy and expresses a comparatively great conformity with experimental data. Then, the aircraft carrier's flow field was calculated by DES. The characteristics of vortexes and velocity fluctuation on the ideal landing track were discussed in different wind directions. Those simulations indicate that there are complicated vortexes produced by blunt edges of the island and deck in the flow field. Those vortexes interact and mainly exist in the rear of flight deck and its adjacent air wake. Moreover, they cause a conspicuous and periodical velocity fluctuation on the ideal landing track as time goes on.

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Zhang, Zhihao, Xiao Liu, Tiezheng Zhao, Gang Liu, Guangpu Lv, and Hongtao Zheng. "Study on combustion characteristics of swirl premixed combustor." Thermal Science and Engineering 4, no. 2 (2021): 62. http://dx.doi.org/10.24294/tse.v4i2.1520.

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Taking a certain type of combustion chamber as the research object, the numerical simulation is carried out by using RANS (Reynolds averaged Navier-stokes) and LES (large eddy simulation), and the simulation results of the two numerical methods are compared and analyzed. The research results show that the RANS calculation results can reflect the main flow field characteristics in the combustion field, and have certain engineering significance. LES can reproduce specific flow field details such as the weak axial flow region, accurately simulate the location and strength of the shear layer, simulate the dynamic development process of flame, and capture the dynamic characteristics of the combustion flow field. Compared with RANS, LES has more obvious advantages in numerical simulation of the combustion flow field. Through calculation, the precessing vortex core under this working condition is composed of three relatively independent spiral vortex branches, which excites periodic velocity pulsation and pressure pulsation in the combustion chamber. LES captures the dominant frequency with the precession vortex core of 156 Hz.

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Kitamura, Masashi, Byungjin An, and Motohiko Nohmi. "Noise prediction of a box fan by RANS simulation." Journal of Physics: Conference Series 2217, no. 1 (2022): 012036. http://dx.doi.org/10.1088/1742-6596/2217/1/012036.

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Abstract The characteristics of aerodynamic performance and aerodynamic noise of a box fan were evaluated to investigate the industrial applicability of computational fluid dynamics (CFD) with Reynolds averaged numerical simulation (RANS) model for fan design. In the case of unsteady RANS, the characteristic of the static pressure rise for flow rates was in good agreement with the experimental results. Aerodynamic noise performance at the design flow rate and low flow rate is well predicted using acoustic/viscous splitting technique based on unsteady RANS with multiple reference frame (MRF). As a result, it was able to evaluate the overall sound characteristic of each fan design relatively. The results suggest that the acoustic/viscous splitting technique based on RANS with MRF simulation has potential as a useful design tool.

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Xiegui, Lu, Chen Qiuhua, Qian Changzhao, and Chen Changping. "Terrain numerical simulation based on RANS/LES hybrid turbulence model." IOP Conference Series: Earth and Environmental Science 356 (October 28, 2019): 012012. http://dx.doi.org/10.1088/1755-1315/356/1/012012.

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Zhang, J. S., Y. Zhang, D. S. Jeng, P. L. F. Liu, and C. Zhang. "Numerical simulation of wave–current interaction using a RANS solver." Ocean Engineering 75 (January 2014): 157–64. http://dx.doi.org/10.1016/j.oceaneng.2013.10.014.

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Hayrullin, A. R., A. I. Haibullina, and V. K. Ilyin. "RANS numerical simulation in in-line tube bundle: prediction of heat transfer." IOP Conference Series: Earth and Environmental Science 979, no. 1 (2022): 012157. http://dx.doi.org/10.1088/1755-1315/979/1/012157.

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Abstract Abstraction. This article analyzed three RANS turbulence models to predict heat transfer in a in-line tube bundle. The numerical simulations were based on the commercial product AnsysFluent. The RNG k-epsilon model with enhanced wall function, SST, SST k-omega models were employed for turbulence modeling. Numerical simulation was carried out in the range of Reynolds numbers from 1000 to 10200. The obtained data on heat transfer were compared with the known empirical equation. The best agreement with experimental data over the entire studied range of the Reynolds number was obtained for the RNG k-epsilon model with enhanced wall function. The average deviation from experimental data was 6.3%.

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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 (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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Hami, Khelifa. "Turbulence Modeling a Review for Different Used Methods." International Journal of Heat and Technology 39, no. 1 (2021): 227–34. http://dx.doi.org/10.18280/ijht.390125.

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This contribution represents a critical view of the advantages and limits of the set of mathematical models of the physical phenomena of turbulence. Turbulence models can be grouped into two categories, depending on how turbulent quantities are calculated: direct numerical simulations (DNS) and RANS (Reynolds Averaged Navier-Stokes Equations) models. The disadvantage of these models is that they require enormous computing power, inaccessible, especially for large and complicated geometries. For this reason, hybrid models (combinations between DNS and RANS methods) have been developed, for example, the LES (“Large Eddy Simulation”) or DES (“Detached Eddy Simulation”) models. They represent a compromise - are less precise than DNS, but more precise than RANS models. The results presented in this contribution will allow and facilitate future research in the field the choice of the model approach necessary for the case studies whatever their difficulty factor.

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SEO, YONGWON, HAENG SIK KO, and SANGYOUNG SON. "MULTIFRACTAL CHARACTERISTICS OF AXISYMMETRIC JET TURBULENCE INTENSITY FROM RANS NUMERICAL SIMULATION." Fractals 26, no. 01 (2018): 1850008. http://dx.doi.org/10.1142/s0218348x18500081.

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A turbulent jet bears diverse physical characteristics that have been unveiled yet. Of particular interest is to analyze the turbulent intensity, which has been a key factor to assess and determine turbulent jet performance since diffusive and mixing conditions are largely dependent on it. Multifractal measures are useful in terms of identifying characteristics of a physical quantity distributed over a spatial domain. This study examines the multifractal exponents of jet turbulence intensities obtained through numerical simulation. We acquired the turbulence intensities from numerical jet discharge experiments, where two types of nozzle geometry were tested based on a Reynolds-Averaged Navier–Stokes (RANS) equations. The [Formula: see text]-[Formula: see text] model and [Formula: see text]-[Formula: see text] model were used for turbulence closure models. The results showed that the RANS model successfully regenerates transversal velocity profile, which is almost identical to an analytical solution. The RANS model also shows the decay of turbulence intensity in the longitudinal direction but it depends on the outfall nozzle lengths. The result indicates the existence of a common multifractal spectrum for turbulence intensity obtained from numerical simulation. Although the transverse velocity profiles are similar for two different turbulence models, the minimum Lipschitz–Hölder exponent [Formula: see text] and entropy dimension [Formula: see text] are different. These results suggest that the multifractal exponents capture the difference in turbulence structures of hierarchical turbulence intensities produced by different turbulence models.

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Strakey, P. A., and M. J. Yip. "Experimental and Numerical Investigation of a Swirl Stabilized Premixed Combustor Under Cold-Flow Conditions." Journal of Fluids Engineering 129, no. 7 (2007): 942–53. http://dx.doi.org/10.1115/1.2743665.

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Planar velocity measurements under cold-flow conditions in a swirl-stabilized dump combustor typical of land-based gas turbine combustors were carried out using two-dimensional particle image velocimetry (PIV). Axial, radial, and tangential velocity components were measured sequentially using two experimental configurations. Mean and root-mean-squared velocity components are presented along with instantaneous realizations of the flowfield. A numerical study of the flowfield using large-eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) techniques was conducted in an effort to help understand the complex hydrodynamics observed in the experiments. The agreement between the experimental data and LES simulation was good with both showing evidence of a precessing vortex core. The results of the RANS simulation were not as encouraging. The results provide a fundamental understanding of the complex flowfield associated with the relatively simple geometry and also serve as a baseline validation dataset for further numerical simulations of the current geometry. Validation of LES models in a highly swirled, nonreacting flowfield such as the work presented here is an essential step towards more accurate prediction in a reacting environment.

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Batrakov, Andrei. "Experimental and numerical simulation of the wall-pressure fluctuation on the isolated helicopter fuselage." EPJ Web of Conferences 269 (2022): 01002. http://dx.doi.org/10.1051/epjconf/202226901002.

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This work is devoted to wall-pressure fluctuation analysis. The object of investigation was an isolated helicopter fuselage. Investigation was carried out by experimental and numerical methods. Numerical simulation was based on RANS and DES approaches. The experiment was carried out in a lowspeed wind tunnel with an open test section. Wall-pressure fluctuation was measurement by high-frequency pressure probes ENDEVCO 8510B-2. The experimental results were compared with both DES data and results by the semi-empirical model based on the RANS simulation. It was shown that DES modelling provides a wall-pressure spectrum for low and middle-frequency parts. For simulation high-frequency part of the spectrum, the semi-empirical model is preferable.

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Yu, Songli, Huichao Dai, Yanwei Zhai, Mengyang Liu, and Wenxin Huai. "A Comparative Study on 2D CFD Simulation of Flow Structure in an Open Channel with an Emerged Vegetation Patch Based on Different RANS Turbulence Models." Water 14, no. 18 (2022): 2873. http://dx.doi.org/10.3390/w14182873.

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Aquatic plants widely exist in rivers, which can affect the flow structure in rivers and have an important impact on the evolution of river morphology. The emerged vegetation is an important member of aquatic vegetation in the river, so studying the flow structure around the emerged vegetation patches is of great significance. Computational fluid dynamics (CFD) simulation provides support for the related research works. Applying the appropriate turbulence model is crucial to achieving realistic numerical simulation results. In this study, two-dimensional numerical simulations were carried out and compared with experimental data by six different Reynolds-Averaged Navier–Stokes (RANS) turbulence models, i.e., Standard k-ε model, Renormalization group (RNG) k-ε model, Realizable k-ε model, Standard k-ω model, Shear-stress transport (SST) k-ω Model, and the Reynolds stress model (RSM). CFD is an effective research method, and the results showed that there are different simulation performances with different turbulence models. The shear stress transport k-ω model achieves the most consistent numerical simulation results with the experimental data for the longitudinal mean flow velocity distribution at the centerline, and the Reynolds stress model provides the least consistent numerical simulation with the experimental data. Then the performance of the six models in simulating the flow field characteristics and longitudinal outflow after vegetation patch was compared.

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Zhang, Shuai, and Adrian Wing-Keung Law. "Performance of Reynolds Averaged Navier–Stokes and Large Eddy Simulation Models in Simulating Flows in a Crossflow Ultraviolet Reactor: An Experimental Evaluation." Water 16, no. 2 (2024): 271. http://dx.doi.org/10.3390/w16020271.

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Computational Fluid Dynamics (CFD) has been increasingly adopted as a design tool for the simulation of UV disinfection efficiency and the optimization of the configuration of a UV reactor. However, the performance of CFD with different turbulence closures may vary significantly. In the present study, an experimental evaluation was performed to assess the performance of CFD with five Reynolds Averaged Navier–Stokes (RANS) turbulence closures and three Large Eddy Simulation (LES) sub-grid scale (SGS) models. A simplified crossflow reactor with a single lamp sleeve was fabricated for the experimental measurements and numerical simulations. Overall, the superior performance of LES compared to RANS models in flow predictions within a complex configuration is demonstrated.

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Wang, Yannan, Lingling Cao, Zhongfu Cheng, Bart Blanpain, and Muxing Guo. "Mathematical Methodology and Metallurgical Application of Turbulence Modelling: A Review." Metals 11, no. 8 (2021): 1297. http://dx.doi.org/10.3390/met11081297.

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This paper focusses on three main numerical methods, i.e., the Reynolds-Averaged Navier-Stokes (RANS), Large Eddy Simulation (LES), and Direct Numerical Simulation (DNS) methods. The formulation and variation of different RANS methods are evaluated. The advantage and disadvantage of RANS models to characterize turbulent flows are discussed. The progress of LES with different subgrid scale models is presented. Special attention is paid to the inflow boundary condition for LES modelling. Application and limitation of the DNS model are described. Different experimental techniques for model validation are given. The consistency between physical experimentation/modelling and industrial cases is discussed. An emphasis is placed on the model validation through physical experimentation. Subsequently, the application of a turbulence model for three specific flow problems commonly encountered in metallurgical process, i.e., bubble-induced turbulence, supersonic jet transport, and electromagnetic suppression of turbulence, is discussed. Some future perspectives for the simulation of turbulent flow are formulated.

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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 (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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Ji, Bai Feng, and Wei Lian Qu. "Transient Simulation of a Three-Dimensional Moving Downburst." Advanced Materials Research 446-449 (January 2012): 3875–78. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.3875.

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Thunderstorm microbursts, which are sources of extreme wind loadings in nature, have caused numerous structural failures, especially collapses of transmission tower around the world. Numerical simulation using computational fluid dynamics (CFD) has recently made significant progress in simulating downbursts. In this paper, transient simulation of a three-dimensional moving downburst was studied using computational fluid dynamics simulation method. Transient simulation of a three-dimensional moving downburst was conducted using time-filtered Reynolds Averaged Navier-Stokes (RANS) numerical simulation method. The three-dimensional transient wind field characteristics in a moving downburst were studied in detail. The results indicate that transient wind field characteristics in a moving downburst present quite different characteristics compared with stationary downburst at different heights and radial positions.

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Bujor, Alexandra Madalina, Andreea Mandru, and Florin Pacuraru. "Numerical simulation of the flow around kayak hull." Analele Universităţii "Dunărea de Jos" din Galaţi Fascicula XI Construcţii navale/ Annals of "Dunărea de Jos" of Galati Fascicle XI Shipbuilding 45 (December 3, 2022): 113–18. http://dx.doi.org/10.35219/annugalshipbuilding/2022.45.13.

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The purpose of this study was to determine the total resistance and investigate the flow around a full-scale kayak. Utilizing Computational Fluid Dynamics(CFD), it was deter-mined how the presence of a rudder affects the kayak hydrodynamic performance. To an-alyse the flow, computational fluid dynamics based on the RANS-VOF solver was em-ployed. The fluid volume approach and the k-ω turbulence model were used in two-phase steady flow simulations around the kayak hulls.

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Muhammed, Manaf, and Muhammad Shakeel Virk. "On the Fidelity of RANS-Based Turbulence Models in Modeling the Laminar Separation Bubble and Ice-Induced Separation Bubble at Low Reynolds Numbers on Unmanned Aerial Vehicle Airfoil." Drones 8, no. 4 (2024): 148. http://dx.doi.org/10.3390/drones8040148.

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The operational regime of Unmanned Aerial Vehicles (UAVs) is distinguished by the dominance of laminar flow and the flow field is characterized by the appearance of Laminar Separation Bubbles (LSBs). Ice accretion on the leading side of the airfoil leads to the formation of an Ice-induced Separation Bubble (ISB). These separation bubbles have a considerable influence on the pressure, heat flux, and shear stress distribution on the surface of airfoils and can affect the prediction of aerodynamic coefficients. Therefore, it is necessary to capture these separation bubbles in the numerical simulations. Previous studies have shown that these bubbles can be modeled successfully using the Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) but are computationally costly. Also, for numerical modeling of ice accretion, the flow field needs to be recomputed at specific intervals, thus making LES and DNS unsuitable for ice accretion simulations. Thus, it is necessary to come up with a Reynolds-Averaged Navier–Stokes (RANS) equation-based model that can predict the LSBs and ISBs as accurately as possible. Numerical studies were performed to assess the fidelity of various RANS turbulence models in predicting LSBs and ISBs. The findings are compared with the experimental and LES data available in the literature. The structure of these bubbles is only studied from a pressure coefficient perspective, so an attempt is made in these studies to explain it using the skin friction coefficient distribution. The results indicate the importance of the use of transition-based models when dealing with low-Reynolds-number applications that involve LSB. ISB can be predicted by conventional RANS models but are subjected to high levels of uncertainty. Possible recommendations were made with respect to turbulence models when dealing with flows involving LSBs and ISBs, especially for ice accretion simulations.

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Muhič, Simon, and Matej Štefanič. "NUMERICAL ANALYSIS OF AN AHMED BODY WITH DIFFERENT SOFTWARE PACKAGES." Journal of Energy Technology 10, no. 1 (2024): 11–21. https://doi.org/10.18690/jet.10.1.11-21.2017.

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In this article, the results of CFD simulations are compared using two different software packages for numerical fluid dynamics. The analysis is performed for an Ahmed body, for which the measurement results and a variety of numerical simulations are available in the literature. The results of the stationary CFD simulations with the RANS approach show a significant difference between the results obtained with the SolidWorks Flow Simulation 2014 software and ANSYS Fluent 16.2 software in the air flow analysis area from 10 m/s to 60 m/s. The difference in computational time is also apparent.

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Premkumar, T. Micha, M. A. Ashish, T. Banu Prakash, and D. Thulasiram. "Numerical Analysis of Wells Turbine." Applied Mechanics and Materials 592-594 (July 2014): 1125–29. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1125.

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In this paper numerical simulation is carried out using commercially available tool Fluent® to predict the performance of a Wells turbine in an oscillating water column wave energy convertor. A wells turbine is the turbo machinery that rotates in same direction as the air flow through the turbine in either axial direction. The main aim of this investigation is to predict complex flow mechanism like separation and recirculation around the turbine blades and subsequently reduction in torque coefficient at higher flow rate. Numerical simulations have been executed by solving the RANS equations together with k-w SST turbulence model. Then a detailed description of flow and overall performance analysis at different flow rate is presented in this paper.

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Ashworth, R. M. "Prediction of acoustic resonance phenomena for weapon bays using detached eddy simulation." Aeronautical Journal 109, no. 1102 (2005): 631–38. http://dx.doi.org/10.1017/s0001924000000968.

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AbstractIt is argued that acoustic resonance phenomena in open cavities such as weapons bays cannot be adequately predicted through numerical solution of Reynolds averaged Navier-Stokes (RANS) equations. The requirement to resolve the growth of the shear layer instability from the lip of the cavity inevitably implies that turbulence further downstream is resolved while also being modelled thus making RANS over dissipative. Large eddy simulation (LES) models only unresolved scales and a hybrid method combining RANS near walls with LES in the cavity appears a practical alternative to pure RANS. This paper compares computations of the M219 cavity configuration made with unsteady RANS and with the hybrid method known as detached eddy simulation (DES). It is shown that whilst unsteady RANS and DES give very similar predictions for the 1stand 3rdmodes of the acoustic resonance the 2ndmode (which is dominant near the centre of the cavity) is absent in the RANS results but well predicted by DES. The 2ndmode is thought to arise from an interaction with vortical structures in the shear layer which are suppressed in the highly dissipative RANS method. The 4thmode, which is much weaker than the other three modes, is over-predicted by DES and under-predicted by a smaller amount in RANS.

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Hasmi, Abrari Noor, and Samsu Dlukha Nurcholik. "THE SIMULATION OF SKEG EFFECT TO BARGE RESISTANCE CALCULATION USING CFD-RANS OPENFOAM." Wave: Jurnal Ilmiah Teknologi Maritim 14, no. 1 (2020): 1–8. http://dx.doi.org/10.29122/jurnalwave.v14i1.3952.

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The paper discusses the significance of different types of skegs in a barge toward the pressure, fluid velocity and the ship’s total resistance. There are three kinds of skeg configurations: barge without skegs, skegs without deflection, and skegs with deflection. The barge was towed with forward speed were ranging across 3 knots – 9 knots. The simulations were conducted using an open-source RANS (Reynold Averaged Numerical Simulation) CFD code Open-FOAM. The simulations show that the skegs raise the barge’s resistance. The skegs with deflection have a bigger resistance amplification compared to skegs without deflection.

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Yin, Hong. "Numerical simulation of swirling flow effect on the first stage vane film cooling distribution." International Journal of Modeling, Simulation, and Scientific Computing 07, no. 03 (2016): 1650031. http://dx.doi.org/10.1142/s1793962316500318.

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In advanced gas turbine technology, lean premixed combustion is an effective strategy to reduce peak temperature and thus, NO[Formula: see text] emissions. The swirler is adopted to establish recirculation flow zone, enhancing mixing and stabilizing the flame. Therefore, the swirling flow is dominant in the combustor flow field and has impact on the vane. This paper mainly investigates the swirling flow effect on the turbine first stage vane cooling system by conducting a group of numerical simulations. Firstly, the numerical methods of turbulence modeling using RANS and LES are compared. The computational model of one single swirl flow field is considered. Both the RANS and LES results give reasonable recirculation zone shape. When comparing the velocity distribution, the RANS results generally match the experimental data but fail to at some local area. The LES modeling gives better results and more detailed unsteady flow field. In the second step, the RANS modeling is incorporated to investigate the vane film cooling performance under the swirling inflow boundary condition. According to the numerical results, the leading edge film cooling is largely altered by the swirling flow, especially for the swirl core-leading edge aligned case. Compared to the pressure side, the suction side film cooling is more sensitive to the swirling flow. Locally, the film cooling jet is lifted and turned by the strong swirling flow.

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Sajjan, Sharanappa, and Siva Kumar. "Numerical Flow Simulation over a Flapping Wing Using Implicit RANS Solver." Frontiers in Aerospace Engineering 5, no. 1 (2016): 29–37. http://dx.doi.org/10.12783/fae.2016.0501.03.

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Azad, Saber, Hamed Amiri Moghadam, Alireza Riasi, and Hossien Mahmoodi Darian. "Numerical simulation of a viscoelastic RANS turbulence model in a diffuser." Korea-Australia Rheology Journal 30, no. 4 (2018): 249–60. http://dx.doi.org/10.1007/s13367-018-0024-8.

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Shu, Shuli, and Ning Yang. "Numerical study and acceleration of LBM-RANS simulation of turbulent flow." Chinese Journal of Chemical Engineering 26, no. 1 (2018): 31–42. http://dx.doi.org/10.1016/j.cjche.2017.05.013.

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Gong, Zhibin, Jie Li, Jixiang Shan, and Heng Zhang. "Numerical Investigation of Powered Jet Effects by RANS/LES Hybrid Methods." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 3 (2019): 565–71. http://dx.doi.org/10.1051/jnwpu/20193730565.

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For the high-precision simulation of engine jet effects, an improved delayed detached eddy simulation (IDDES) method based on the two-equation shear stress transport (SST) model is developed, and the fifth-order finite-volume weighted essentially non-oscillatory (WENO) scheme is employed to enhance accuracy of spatial discretization, and then numerical investigation of powered jet effects by RANS/LES hybrid methods is carried out. The effects of the grid distributions and the accuracy of the spatial schemes are discussed during the RANS/LES validation analysis on the fully expanded jet flow and Acoustic Reference Nozzle (ARN) jet flow. The results show that, by enlarging the grid density and improving the accuracy of the spatial schemes, the velocity distributions in the jet flow can be better predicted, the non-physical steady flow after the jet nozzle can be shortened, the instantaneous flow structures are clearer and the turbulent intensities are more accurate. Then IDDES simulation of turbofan engine jet flow is carried out. The mixing characteristics of the external fan jet flow and internal core jet flow as well as the ambient flow are obtained, and the three-dimensional turbulent structures are also given.

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Li, Tian, Hassan Hemida, and Jiye Zhang. "Evaluation of SA-DES and SST-DES models using OpenFOAM for calculating the flow around a train subjected to crosswinds." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 10 (2019): 1346–57. http://dx.doi.org/10.1177/0954409719895652.

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Detached eddy simulation (DES) has been widely applied in crosswind stability simulations of trains in recent years. As DES is a hybrid Reynolds Averaged Navier–Stokes (RANS)/large eddy simulation approach, the choice of the RANS model associated with DES is a key factor for an accurate numerical simulation. However, the influence of the RANS model on the flow around trains was not fully investigated in previous researches. In this study, DES with the Spalart–Allmaras (SA) model (SA-DES) and shear stress transport (SST) k−ω model (SST-DES) have been investigated owing to their ability to predict the surface pressure, aerodynamic forces, and the flow field around a 1/25th scale Class 390 train subjected to crosswinds. Numerical simulation results were validated with experimental data. Results show that both SA-DES and SST-DES predict similar trends of the mean flow field around the train. However, there were considerable differences observed in the position of separation points and consequently the separation and attachment lines on the roof and bottom of the train body. The SST-DES results correlated more closely to the experimental data than SA-DES for pressure coefficient on the roof and leeward surface at almost all loops. A slight difference in the side force and roll moment coefficients and a considerable difference in the lift force coefficient were observed for SA-DES and SST-DES. The side force coefficients calculated using SST-DES remain within the experimental uncertainty, whereas the lift force coefficients deviated greatly due to the omission of some underbody geometrical features. Compared to the experimental data, the SST-DES performs better than SA-DES. Therefore, the SST k−ω model is recommended for the RANS model associated with DES.

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Li, Zhi Chuan, Qi Hu Sheng, Liang Zhang, Zhi Ming Cong, and Jin Jiang. "Numerical Simulation of Blade-Wake Interaction of Vertical Axis Tidal Turbine." Advanced Materials Research 346 (September 2011): 318–23. http://dx.doi.org/10.4028/www.scientific.net/amr.346.318.

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To study the blade-wake interaction of vertical axis tidal turbine (VATT)，particles were placed in the flow field to trace blade wake during numerical simulation. Numerical simulations were conducted utilizing Euler-Lagrange model. In the simulations, the continuous phase was solved by Reynolds-averaged Navier-Stocks(RANS) equation combined with SST turbulence model and the particle trajectories of the dispersed phase were determined by momentum equation. Numerical results of predicting instantaneous blade forces and blade wakes showed good agreement with the test data. The model was also compared with previous classic free vortex model (V-DART), vortex method combined with finite element analysis (FEVDTM) and 2-D vortex panel model (VPM2D). It showed that the present model was much better than the former.

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Zhang, Shudi, Hongwei Li, Tiedong Zhang, Yongjie Pang, and Qinglong Chen. "Numerical Simulation Study on the Effects of Course Keeping on the Roll Stability of Submarine Emergency Rising." Applied Sciences 9, no. 16 (2019): 3285. http://dx.doi.org/10.3390/app9163285.

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A direct numerical simulation method based on Reynolds Average Navier–Stokes (RANS) equations is used to carry out numerical prediction studies of submarine emergency rising in this paper. Firstly, a numerical simulation of the nonpropelled model without rudder manipulating is accomplished as the basis of this study. The numerical prediction results are in good agreement with the experimental data, which proves the feasibility and accuracy of the direct numerical simulation method. Meanwhile, both model tests and numerical simulation results reveal the strong coupling effect between roll and yaw motions during the underwater ascending process. Based on the above observation and analysis, another two numerical simulations, whose grids are identical with the non-manipulation simulation, are conducted respectively under the condition of rudder steering, i.e., course keeping simulation and self-propulsion simulation. An optimized S surface controller based on conditional determination is designed to manipulate the rudders. As a result, the yaw angle of the latter two simulations is limited within the range of 0.2° and 0.8° respectively, proving the effectiveness of the S surface controller. Correspondingly, the maximum roll angle is reduced by 96% and 70% respectively, which demonstrates that the roll stability is significantly enhanced by improving the course keeping ability of the model. Moreover, it is also proven from the perspective of reverse verification that, the excessive yaw deviation is the root cause of emergency rising roll instability for the situation of incidence angle lower than 30°.

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Fu, Weijia, Jingzhong Ma, and Jie Li. "Investigation of Rotor Tip Vortex in Hover Based on IDDES Methods." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 1 (2019): 195–202. http://dx.doi.org/10.1051/jnwpu/20193710195.

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A calculation and analysis program of high-precision numerical simulation for rotor blade tip vortex in hovering state was developed. The fifth order Roe-WENO scheme was carried out in order to reduce the numerical dissipation of the rotor wake region. The rotary motion of the rotor was realized by using the dynamic patched technology of structured grids. And at the same time, the technology also helped to avoid the tremendous increase of grid number of the far-field due to the refined grids of the flow region where emphasis was placed on. Hybrid RANS/LES approach was investigated based on the issues about inadequate capabilities of simulations of complex turbulent flows, and IDDES approach was developed. The numerical simulation of the tandem cylinder was carried out firstly to verify the reliability of the IDDES method and the patched grid technology. Then the RANS and IDDES approaches were used to simulate the flow field of the rotor in hover performance, respectively. The analysis of the vortex magnitude, vortex core position and diameter as well as the velocity profiles of the rotor tip vortex were made comparatively in detail. The numerical results showed that the resolutions obtained through IDDEES approach agreed with the experimental results much better than that of the RANS approach with the same gird scales. Meanwhile, the IDDES results can capture the tiny worm vortex structures and vortex paring phenomena in accordance with the practical status, which contributes to study the flow mechanism of rotor and related problems.

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Tian, Chunlai, Tairan Chen, and Tian Zou. "Numerical study of unsteady cavitating flows with RANS and DES models." Modern Physics Letters B 33, no. 20 (2019): 1950228. http://dx.doi.org/10.1142/s0217984919502282.

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Unsteady cavitating flow with high Reynolds number and significant instability commonly exists in fluid machinery and engineering system. The high-resolution approaches, such as direct numerical simulation and large eddy simulation, are not practical for engineering issues due to the significant cost in the computational resource. The objective of this paper is to provide the approach with Detached-Eddy Simulation (DES) model based on the Reynolds-averaged Navier–Stokes (RANS) equations for predicting unsteady cavitating flows. The credibility of the approach is validated by a set of numerical examples of its application: the unsteady cavitating flows around the two-dimensional (2D) Clark-Y hydrofoil and the three-dimensional (3D) blunt body. It is found that the calculated cavity shapes, cavity lengths and unsteady characteristics by DES model agree well with the experimental measurements and observations. Further analysis indicates that the turbulent eddy viscosity around the cavity and wake region is well predicted by the DES model, which results in the development of large-scale vortexes, and further cavitation instability. The DES model, which exhibits a significantly unsteady 3D behavior, is a more comprehensive turbulence model for unsteady cavitating flows.

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Stabnikov, A. S., D. K. Kolmogorov, A. V. Garbaruk, and F. R. Menter. "Direct Numerical Simulation of separated turbulent flow in axisymmetric diffuser." Journal of Physics: Conference Series 2103, no. 1 (2021): 012214. http://dx.doi.org/10.1088/1742-6596/2103/1/012214.

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Abstract Direct numerical simulation (DNS) of the separated flow in axisymmetric CS0 diffuser is conducted. The obtained results are in a good agreement with experimental data of Driver and substantially supplement them. Along with other data, eddy viscosity extracted from performed DNS could be used for RANS turbulence model improvement.

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Merder, T., M. Warzecha, and P. Warzecha. "Large-Eddy Simulations of a Flow Characteristics in a Multi-Strand Continuous Casting Tundish / Badania Numeryczne Charakterystyk Przepływu W Wielo-Wylewowej Kadzi Posredniej Metodą Wielkich Wirów (Les)." Archives of Metallurgy and Materials 60, no. 4 (2015): 2923–26. http://dx.doi.org/10.1515/amm-2015-0466.

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In order to increase the efficiency and quality of the steel-making process a numerous studies are conducted at the various stages of the process, including continuous casting of steel. Researchers still search for new models and improve existing one, so that the specific of the process is accuratelly reproduced. One way to increase the accuracy of numerical simulation, is to apply the LES (Large Eddy Simulation) method to simulate steelmaking processes. The article presents the results of numerical analysis on the flow characteristics (RTD curves) of liquid steel in the tundish facility for the continuous casting of steel. Numerical simulations have been performed using RANS (Reynoldsaveraged Navier-Stoke) and LES methods, and those results have been verified in industrial conditions.

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Weymouth, Gabriel David, Robert Vance Wilson, and Frederick Stern. "RANS Computational Fluid Dynamics Predictions of Pitch and Heave Ship Motions in Head Seas." Journal of Ship Research 49, no. 02 (2005): 80–97. http://dx.doi.org/10.5957/jsr.2005.49.2.80.

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This work extends the previous effort in unsteady Reynolds averaged Navier-Stokes (RANS) simulations developed by the ship hydrodynamics group of the University of Iowa Iowa Institute of Hydraulic Research to the capability to predict pitch and heave motions of ships with forward speed in regular head seas. The simulations are performed with CFDSHIP-IOWA, which is a general-purpose, multiblock, high-performance parallel computing RANS code. Numerical verification studies in space and time demonstrate convergence for nearly all variables. The modified Wigley hull form experimental data presented in Journee (1992) are compared with simulation results over a range of Froude numbers, wavelengths, and wave amplitudes and found to give accurate results, with uncertainties less than 2%. Viscous ship motions characteristics are investigated by decomposing the full nonlinear problem into the forward speed diffraction and pitch and heave radiation problems, in the manner of strip theory. Comparisons between the current viscous RANS solutions and those from experiments, strip theory, and nonlinear potential flow simulations show the RANS method to predict damping and added mass coefficients with a high degree of accuracy.

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Lushchik, V. G., M. S. Makarova, and A. I. Reshmin. "Numerical Simulation of Turbulent Flow Control." Известия Российской академии наук. Механика жидкости и газа, no. 1 (January 1, 2023): 81–96. http://dx.doi.org/10.31857/s0568528122600473.

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Various methods of flow relaminarization in a pipe are considered by means of controlling the average and turbulent flow parameters. For numerical simulation of flows with turbulence growth and suppression it is proposed to use a three-parameter RANS turbulence model, which has shown good results in modeling existing experiments on relaminarization. Calculations for three variants of inlet devices with different velocity profiles and the same small-scale turbulence at the inlet show the possibility of achieving flow relaminarization in pipes at Reynolds numbers Re 10000. Among three variants of inlet devices considered, the most effective one is the variant with organization of a twozone flow with slow flow in the central region of the pipe and accelerated flow in the near-wall region. In this version, relaminarization occurs up to the Reynolds number Re* = 16000. It is shown that decrease in the turbulence intensity and scale leads to an even larger value of the relaminarization Reynolds number Re*.

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Du, Xiaoxu, and Zhengdong Zhang. "Numerical Simulation Analysis of Cavitation Performance of Tandem Propeller." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, no. 3 (2018): 509–15. http://dx.doi.org/10.1051/jnwpu/20183630509.

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Анотація:

The steady non cavitation hydrodynamic characteristics of CLB4-55-1 tandem propeller and the steady cavitation flows of NACA66 hydrofoil are numerically studied firstly based on the RANS equations of homogeneous multiphase using CFD theory, combined with the SST k-ω turbulent model and Z-G-B cavitation model. Numerical simulation results are in good agreement with the experimental results, which indicates that the numerical method is reliable and accurate. Then, the cavitation performance of the tandem propeller are numerical simulated and analyzed. The results show that the computational model can predict the cavitation performance of tandem propeller accurately. The cavitation performance of tandem propeller is nearly the same as single propeller, however, the cavitation phenomenon of back propeller is greater than the head propeller at certain advance coefficient and cavitation number. The cavitation phenomenon will disappear with the increase of the advance coefficient or the cavitation number.

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