Статті в журналах: "RANS numerical simulation"

1

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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2

Viti, Nicolò, Daniel Valero, and Carlo Gualtieri. "Numerical Simulation of Hydraulic Jumps. Part 2: Recent Results and Future Outlook." Water 11, no. 1 (December 24, 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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3

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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4

Ketong, Liu, and Tang Aiping. "Numerical Investigation for Aerodynamic Derivatives of Bridge Deck Using DES." Open Civil Engineering Journal 8, no. 1 (December 24, 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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5

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 (June 1, 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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6

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 (July 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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7

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 (July 28, 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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8

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 (November 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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9

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 (December 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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10

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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11

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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12

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 (October 26, 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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13

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 (February 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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14

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 (May 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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15

Kitamura, Masashi, Byungjin An, and Motohiko Nohmi. "Noise prediction of a box fan by RANS simulation." Journal of Physics: Conference Series 2217, no. 1 (April 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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16

SEO, YONGWON, HAENG SIK KO, and SANGYOUNG SON. "MULTIFRACTAL CHARACTERISTICS OF AXISYMMETRIC JET TURBULENCE INTENSITY FROM RANS NUMERICAL SIMULATION." Fractals 26, no. 01 (February 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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17

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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18

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 (November 13, 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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19

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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20

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 (November 2018): 249–60. http://dx.doi.org/10.1007/s13367-018-0024-8.

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21

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

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22

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 (January 18, 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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23

Hami, Khelifa. "Turbulence Modeling a Review for Different Used Methods." International Journal of Heat and Technology 39, no. 1 (February 28, 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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24

Minakov, A., D. Platonov, A. Sentyabov, and A. Gavrilov. "Francis-99 turbine numerical flow simulation of steady state operation using RANS and RANS/LES turbulence model." Journal of Physics: Conference Series 782 (January 2017): 012005. http://dx.doi.org/10.1088/1742-6596/782/1/012005.

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25

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 (November 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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26

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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27

Ashworth, R. M. "Prediction of acoustic resonance phenomena for weapon bays using detached eddy simulation." Aeronautical Journal 109, no. 1102 (December 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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28

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 (May 29, 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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29

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 (August 23, 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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Cremades Rey, Luis F., Denis F. Hinz, and Mahdi Abkar. "Reynolds Stress Perturbation for Epistemic Uncertainty Quantification of RANS Models Implemented in OpenFOAM." Fluids 4, no. 2 (June 22, 2019): 113. http://dx.doi.org/10.3390/fluids4020113.

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Reynolds-averaged Navier-Stokes (RANS) models are widely used for the simulation of engineering problems. The turbulent-viscosity hypothesis is a central assumption to achieve closures in this class of models. This assumption introduces structural or so-called epistemic uncertainty. Estimating that epistemic uncertainty is a promising approach towards improving the reliability of RANS simulations. In this study, we adopt a methodology to estimate the epistemic uncertainty by perturbing the Reynolds stress tensor. We focus on the perturbation of the turbulent kinetic energy and the eigenvalues separately. We first implement this methodology in the open source package OpenFOAM. Then, we apply this framework to the backward-facing step benchmark case and compare the results with the unperturbed RANS model, available direct numerical simulation data and available experimental data. It is shown that the perturbation of both parameters successfully estimate the region bounding the most accurate results.

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31

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 (June 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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32

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 (July 18, 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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33

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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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 (August 17, 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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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 (September 15, 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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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 (June 2018): 509–15. http://dx.doi.org/10.1051/jnwpu/20183630509.

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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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37

Zhang, Bao-Ji, Jie Liu, Ning Xu, Lei Niu, and Wen-Xuan She. "Numerical Simulation of Ship Motions in Regular and Irregular Waves." Marine Technology Society Journal 53, no. 1 (January 1, 2019): 97–106. http://dx.doi.org/10.4031/mtsj.53.1.10.

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AbstractA numerical simulation method is presented in this study to predict ship resistance and motion responses in regular and irregular waves. The unsteady RANS (Reynolds Average Navier-Stokes) method is selected as the governing equation, and a volume of fluid (VoF) model is used to capture the free surface, combining the k-ε equations. A finite volume method (FVM) is utilized to discretize both the RANS equations and VoF transport equation. The pressure implicit split operator (PISO) method is set as the velocity-pressure coupling equation. The overset mesh technique is utilized to simulate ship motions in waves. A DTMB5415 ship is selected as a case study to predict its pitch and heave responses in regular and irregular waves at different wave length and wave steepness. The ship is free to move in the pitch and heave directions. The CFD (Computational Fluid Dynamics) results are found to be in good agreement with the strip theory and experimental data. It can be found that the CFD method presented in this study can provide a theoretical basis and technical support for green design and manufacture of ships.

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38

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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39

Tang, Shang Qin, and Chang Qiang Huang. "Comparative Study of Synthetic Jet Numerical Simulation Methods." Applied Mechanics and Materials 275-277 (January 2013): 486–90. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.486.

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In order to find the best synthetic jet model for active flow control numerical simulation study, exit velocity model, simply connected domain model and moving boundary model were researched through solving the two dimensional transient Reynolds Average Navier-Stokes(RANS) equations under consistent grid and boundary conditions. Velocity and vortex characteristics of flow field were got. Three models were all able to capture the velocity characteristics compared with experiment data. The moving boundary model can capture the distribution of vortices accurately and was the ideal model for applications, because it considered the spatial distribution and time distribution of diaphragm motion, also because it included the volume change rate of actuator cavity.

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40

Hanjalić, K., and S. Kenjereš. "RANS-Based Very Large Eddy Simulation of Thermal and Magnetic Convection at Extreme Conditions." Journal of Applied Mechanics 73, no. 3 (October 2, 2005): 430–40. http://dx.doi.org/10.1115/1.2150499.

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For thermal and magnetic convection at very high Rayleigh and Hartman numbers, which are inaccessible to the conventional large eddy simulation, we propose a time-dependent Reynolds-average-Navier-Stokes (T-RANS) approach in which the large-scale deterministic motion is fully resolved by time and space solution, whereas the unresolved stochastic motion is modeled by a “subscale” model for which an one-point RANS closure is used. The resolved and modeled contributions to the turbulence moments are of the same order of magnitude and in the near-wall regions the modeled heat transport becomes dominant, emphasizing the role of the subscale model. This T-RANS approach, with an algebraic stress/flux subscale model, verified earlier in comparison with direct numerical simulation and experiments in classic Rayleigh-Bénard convection, is now expanded to simulate Rayleigh-Bénard (RB) convection at very high Ra numbers—at present up to O(1016)—and to magnetic convection in strong uniform magnetic fields. The simulations reproduce the convective cell structure and its reorganization caused by an increase in Ra number and effects of the magnetic field. The T-RANS simulations of classic RB indicate expected thinning of both the thermal and hydraulic wall boundary layer with an increase in the Ra number and an increase in the exponent of the Nu∝Ran correlation in accord with recent experimental findings and Kraichnan asymptotic theory.

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Scotton, Jaque W., Zardo Becker, Darci L. Savicki, and Antonio Goulart. "Mathematical Modeling and Numerical Simulation of Atmospheric Pollutant Dispersion." Defect and Diffusion Forum 372 (March 2017): 180–87. http://dx.doi.org/10.4028/www.scientific.net/ddf.372.180.

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This work presents a mathematical modeling and numerical solution of dispersion of pollutants in the atmosphere. The equations of conservation of mass, amount of movement, energy and a chemical species are solved by the Finite Volume Method in Cartesian coordinates and the turbulence closure is based on the Reynolds averages (RANS models), using the model k-ε for the determination of the fields of velocity, temperature and, in a specific case, concentration of pollutant. The numerical results are compared with data from the classic Prairie Grass experiment, showing excellent agreement.

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42

Liu, Yuan, Edgar A. Matida, Junjie Gu, and Matthew R. Johnson. "Numerical simulation of aerosol deposition in a 3-D human nasal cavity using RANS, RANS/EIM, and LES." Journal of Aerosol Science 38, no. 7 (July 2007): 683–700. http://dx.doi.org/10.1016/j.jaerosci.2007.05.003.

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43

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 (December 25, 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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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 (June 1, 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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45

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 (February 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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Jeong, Jae-ho, and Kwangtae Ha. "Evaluation of Wind Flow Characteristics by RANS-Based Numerical Site Calibration (NSC) Method with Met-Tower Measurements and Its Application to a Complex Terrain." Energies 13, no. 19 (October 1, 2020): 5121. http://dx.doi.org/10.3390/en13195121.

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The performance of wind turbines is not only dependent on the wind turbine design itself, but is also dependent on the accurate assessment of wind resources at the installation site. In this paper, the numerical site calibration (NSC) method using three-dimensional Reynolds-averaged Navier–Stokes (RANS) simulation was proposed to accurately forecast the wind flow characteristics of wind turbine sites with complex terrains, namely Methil in Scotland, and Haenam in South Korea. From NSC at the Methil and Haenam sites, it was shown that the complicated and vortical flow fields around hills and valleys were captured using the three-dimensional RANS CFD simulation in Ansys CFX software based on a high-resolution scheme with a renormalization group (RNG)-based k-ε turbulence model. It was also shown that topographically induced wind profile and turbulence intensity over a local-scale complex terrain are remarkably dominated by flow separation after passing hills. It was concluded that the proposed NSC method using three-dimensional RANS simulation with a high-resolution scheme was an economically useful method for evaluating wind flow characteristics numerically to assess wind turbine sites with complex terrains and designing the wind farm layout.

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47

Ali, Md Shahjahan, Takashi Hosoda, and Ichiro Kimura. "Unsteady RANS and LES Simulation of an Ideal Rankine Vortex Decay." Advances in Civil Engineering 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/523839.

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The 3D numerical simulation was carried out for an idealized Rankine vortex using nonlineark-εmodel (one kind of RANS model) and large eddy simulation (LES) techniques. In this 3D simulation, the vortex flow field was given to rotate with the vertical axis in a free surface rectangular domain. In order to investigate the predictability of standard (linear) and non-lineark-εmodels, the decay of a trailing vortex was simulated and compared with previous DNS data. The governing equations for mean velocities and turbulent flows were discretized with the finite volume method based on a staggered grid system. It was observed that in the growth phase as well as in stabilized phase of turbulence, the decay rate of tangential velocity by RANS model was well comparable with LES simulation as well as previous DNS data. However, in the decay phase of turbulence, RANS model showed slightly faster decay of tangential velocity due to its slower decay of turbulence compared to LES or DNS. The patterns as well as magnitudes of secondary currents predicted by RANS and LES models were well comparable to each other.

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48

Chen, Binqi, and Yiding Wang. "Nonlinear Numerical Simulation for Oscillating Pressure in Cavity and Passive Control Research." International Journal of Aerospace Engineering 2019 (December 20, 2019): 1–12. http://dx.doi.org/10.1155/2019/4153287.

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Prediction of oscillating pressure is a key technology for cavity research. Nonlinear Acoustic Solver (NLAS) is applied to analyze aeroacoustics recently. A nonlinear numerical solver is combined with the Reynolds-averaged Navier-Stokes (RANS) method. RANS is applied to solving the flow field around a cavity, and average solution of initial turbulent statistics is obtained which contains the basic characteristics of the average flow field and statistic description of turbulence fluctuation. The source of acoustic generation is reconstructed, and the spreading of oscillating pressure is simulated precisely. According to the comparison of the cavity noise calculation and experimental results under Mach numbers 0.6, 0.85, and 1.35, it indicates that NLAS is capable to predict oscillating pressure of cavity flow from subsonic to supersonic with acceptable deviation. On this basis, the contribution to oscillating pressure suppression made by passive control such as rectangular fence (RF) and square tooth spoiler (STS) is investigated. It is found that these two passive control methods can lessen the total noise.

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49

Dang, Tien Phuc, Zhengqi Gu, and Zhen Chen. "Numerical simulation of flow field around the race car in case." International Journal of Numerical Methods for Heat & Fluid Flow 25, no. 8 (November 2, 2015): 1896–911. http://dx.doi.org/10.1108/hff-04-2014-0107.

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Purpose – The purpose of this paper is to gain a better understanding of the flow field structure around the race car in two cases: stationary wheel and rotating wheel. In addition, this paper also illustrates and clarifies the influence of wheel rotation on the aerodynamic characteristics around the race car. Design/methodology/approach – The author uses steady Reynolds-Averaged Navier-Stokes (RANS) equations with the Realizable k-ε model to study model open-wheel race car. Two cases are considered, a rotating wheel and stationary wheel. Findings – The results obtained from the study are presented graphically, pressure, velocity distribution, the flow field structure, lift coefficient (Cl) and drag coefficient (Cd) for two cases and the significant influence of rotating case on flow field structure around wheel and aerodynamic characteristics of race car. The decreases in Cd and Cl values in the rotating case for the race car are 16.83 and 13.25 per cent, respectively, when compared to the stationary case. Originality/value – Understanding the flow field structures and aerodynamic characteristics around the race car in two cases by the steady RANS equations with the Realizable k-ε turbulence model.

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50

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 (December 1, 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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