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1
Deng, Yilin, Jian Feng, Fulai Wan, Xi Shen, and Bin Xu. "Evaluation of the Turbulence Model Influence on the Numerical Simulation of Cavitating Flow with Emphasis on Temperature Effect." Processes 8, no. 8 (2020): 997. http://dx.doi.org/10.3390/pr8080997.
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The aim of this paper is to investigate the influence of different turbulence models (k−ε, RNG k−ε, and SST k−ω) on the numerical simulation of cavitating flow in thermosensitive fluid. The filter-based model and density correction method were employed to correct the turbulent viscosity of the three turbulence models. Numerical results obtained were compared to experimental ones which were conducted on the NACA0015 hydrofoil at different temperatures. The applicability of the numerical solutions of different turbulence model was studied in detail. The modified RNG k−ε model has higher accuracy in the calculation of cavitating flow at different temperatures.
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Wang, Peng, and Hai Lin Mu. "Impact of Different Turbulence Models on Air Pollutant Flow and Distribution." Key Engineering Materials 439-440 (June 2010): 1373–78. http://dx.doi.org/10.4028/www.scientific.net/kem.439-440.1373.
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The aim of this study is to provide a simulation of air pollutant in a street canyon and investigates the impact of different turbulence models on the flow structure and air pollutant dispersion. Three studied k-ε turbulence models are evaluated to determine the most optimum turbulence model and the most suitable parameters of inlet boundary velocity and turbulent kinetic energy for simulating the pollutant dispersion in the present street canyon. The calculated data of the numerical model are then validated by comparing the extensive experimental database obtained from Kastner-Klein and Plate. Compared with the measured results, it can be concluded that modified RNG model with the inlet velocity profile and turbulent kinetic energy and turbulent dissipation rate provides the best calculated results, while standard and RNG k-ε turbulence models under-predict the pollutant concentrations.
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Teixeira, Christopher M. "Incorporating Turbulence Models into the Lattice-Boltzmann Method." International Journal of Modern Physics C 09, no. 08 (1998): 1159–75. http://dx.doi.org/10.1142/s0129183198001060.
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The Lattice-Boltzmann method (LBM) is extended to allow incorporation of traditional turbulence models. Implementation of a two-layer mixing-length algebraic model and two versions of the k-ε two-equation model, Standard and RNG, in conjunction with a wall model, are presented. Validation studies are done for turbulent flows in a straight pipe at three Re numbers and over a backwards facing step of expansion ratio 1.5 and Re H=44 000. All models produce good agreement with experiment for the straight pipes but the RNG k-ε model is best able to capture both the recirculation length, within 2% of experiment, and the detailed structure of the mean fluid flow for the backwards facing step.
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Hossain, Md Safayet, Md Ishtiaque Hossain, Somit Pramanik, and Dr Jamal Uddin Ahamed. "Analyzing the Turbulent Flow Characteristics by Utilizing k-? Turbulence Model." European Journal of Engineering and Technology Research 2, no. 11 (2017): 28–34. http://dx.doi.org/10.24018/ejeng.2017.2.11.510.
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This study attempts to illustrate the behavior of a fully developed turbulent flow by using k-? turbulence model. A two dimensional smooth bend channel is adopted for this experiment and water was chosen as working fluid. The Reynolds number was gradually increased to predict the diversity in turbulent kinetic energy (TKE), turbulent dissipation rate, turbulent intensity and eddy viscosity. Primarily the flow has been solved by employing three distinct k-? turbulence models namely, Standard, Renormalization-group (RNG) and Realizable model. After experimenting with ten different sample (from 74E03 to 298E03) of Reynolds numbers, each of these analyses explicitly showed that Standard k-? model gives much higher value of any aforementioned turbulent properties with respect to other two equation turbulence models. Later it’s been discovered that TKE obtained from Standard k-? model is almost same as Realizable k-? model (for Re=298E03, the difference is about 1.8%). It has been observed that the skin friction coefficient at the bend region obtained from different two equation models (Standard, Realizable and RNG k-? model and Standard k-? model) are almost similar to each other for each sample of Reynolds number. Quadrilateral elements were taken into consideration for grid generation in this analysis. Also, to decrease cost and to achieve further accuracy as well as reduced time consumption mapped faced meshing was utilized.
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Zhao, Xingwang, та Qingyan Chen. "Optimal design of an indoor environment using an adjoint RNG k-ε turbulence model". E3S Web of Conferences 111 (2019): 04037. http://dx.doi.org/10.1051/e3sconf/201911104037.
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The computational fluid dynamics (CFD)-based adjoint method can determine design variables of an indoor environment according to the optimal design objective, such as minimal predicted mean vote (PMV) for thermal comfort. The method calculates the gradient of the objective function over the design variables so that the objective function can be minimized along the fastest direction using an optimization algorithm. Since the RNG k-ε model is the most popular model used in CFD, the corresponding adjoint equations of the turbulence model should be solved during the design process, rather than the “frozen turbulence” assumption used in the existing approach. This investigation developed adjoint equations for the RNG k-ε turbulence model and applied it to a two-dimensional ventilated cavity. Design processes with the adjoint RNG k-ε turbulence model led to a near-zero design function for the cavity case, while that one with the RNG k-ε turbulence model did not.
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Hossain, Md Safayet, Md Ishtiaque Hossain, Somit Pramanik та Dr Jamal Uddin Ahamed. "Analyzing the Turbulent Flow Characteristics by Utilizing k-ϵ Turbulence Model." European Journal of Engineering Research and Science 2, № 11 (2017): 28. http://dx.doi.org/10.24018/ejers.2017.2.11.510.
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This study attempts to illustrate the behavior of a fully developed turbulent flow by using k-ε turbulence model. A two dimensional smooth bend channel is adopted for this experiment and water was chosen as working fluid. The Reynolds number was gradually increased to predict the diversity in turbulent kinetic energy (TKE), turbulent dissipation rate, turbulent intensity and eddy viscosity. Primarily the flow has been solved by employing three distinct k-ϵ turbulence models namely, Standard, Renormalization-group (RNG) and Realizable model. After experimenting with ten different sample (from 74E03 to 298E03) of Reynolds numbers, each of these analyses explicitly showed that Standard k-ε model gives much higher value of any aforementioned turbulent properties with respect to other two equation turbulence models. Later it’s been discovered that TKE obtained from Standard k-ω model is almost same as Realizable k-ε model (for Re=298E03, the difference is about 1.8%). It has been observed that the skin friction coefficient at the bend region obtained from different two equation models (Standard, Realizable and RNG k-ϵ model and Standard k-ω model) are almost similar to each other for each sample of Reynolds number. Quadrilateral elements were taken into consideration for grid generation in this analysis. Also, to decrease cost and to achieve further accuracy as well as reduced time consumption mapped faced meshing was utilized.
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Owolabi, Jibola, Khawaja Hassan, and Amar Aganovic. "Comparative Evaluation of Four RANS Turbulence Models for Aerosol Dispersion from a Cough." E3S Web of Conferences 396 (2023): 01072. http://dx.doi.org/10.1051/e3sconf/202339601072.
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The study of aerosol dispersion in indoor environments is essential to understanding and mitigating airborne virus transmission, such as SARS-CoV-2. Computational Fluid Dynamics (CFD) has emerged as a valuable tool for investigating aerosol dispersion, providing an alternative to costly experimental methods. In this study, we investigated the performance of four (4) Reynolds-averaged Navier-Stokes (RANS) turbulence models in predicting aerosol dispersion from a human body coughing in a small, ventilated indoor environment. We compared the Standard, RNG, Realizable k-ϵ models and the SST k- ω model using the same boundary conditions. We initially observed that the horizontal distance of the coughed aerosols after 10.2s dispersion time was substantially shorter with the standard k-ϵ turbulence compared to the other three turbulence models compared to the SST k-ω model, the RNG, and realizable k-ϵ models exhibit a high degree of similarity in their dispersion patterns. Specifically, we observed that the aerosols dispersed horizontally faster with the RNG and Realizable k-ϵ models. In conclusion, when compared to qualitative data from the literature, our observations exclude the standard k-ϵ turbulence. However, to select the most appropriate turbulence model for capturing the cough flow and aerosol dispersion dynamics, further detailed validation against both quantitative and qualitative data is needed.
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Coutier-Delgosha, O., R. Fortes-Patella, and J. L. Reboud. "Evaluation of the Turbulence Model Influence on the Numerical Simulations of Unsteady Cavitation." Journal of Fluids Engineering 125, no. 1 (2003): 38–45. http://dx.doi.org/10.1115/1.1524584.
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Unsteady cavitation in a Venturi-type section was simulated by two-dimensional computations of viscous, compressible, and turbulent cavitating flows. The numerical model used an implicit finite volume scheme (based on the SIMPLE algorithm) to solve Reynolds-averaged Navier-Stokes equations, associated with a barotropic vapor/liquid state law that strongly links the density variations to the pressure evolution. To simulate turbulence effects on cavitating flows, four different models were implemented (standard k-ε RNG; modified k-ε RNG; k-ω with and without compressibility effects), and numerical results obtained were compared to experimental ones. The standard models k-ε RNG and k-ω without compressibility effects lead to a poor description of the self-oscillation behavior of the cavitating flow. To improve numerical simulations by taking into account the influence of the compressibility of the two-phase medium on turbulence, two other models were implemented in the numerical code: a modified k-ε model and the k-ω model including compressibility effects. Results obtained concerning void ratio, velocity fields, and cavitation unsteady behavior were found in good agreement with experimental ones. The role of the compressibility effects on turbulent two-phase flow modeling was analyzed, and it seemed to be of primary importance in numerical simulations.
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Budiarso, Ahmad Indra Siswantara, Steven Darmawan та Harto Tanujaya. "Inverse-Turbulent Prandtl Number Effects on Reynolds Numbers of RNG k-ε Turbulence Model on Cylindrical-Curved Pipe". Applied Mechanics and Materials 758 (квітень 2015): 35–44. http://dx.doi.org/10.4028/www.scientific.net/amm.758.35.
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Inverse-turbulent Prandtl number (α) is one of important parameters on RNG k-ε turbulence model which represent the cascade energy of the flow, which occur in cylindrical curved-pipe. Although many research has been done, turbulent flow in curved pipe is still a challanging problem. The range of α of the basic RNG k-ε turbulence model described by Yakhot and Orszag (1986) with range 1-1.3929 has to be more specific on Reynolds number (Re) and geometry. However, since the viscosity is sensitive to velocity and temperature, the reference of α is needed on specific range of Reynolds number. This paper is aimed to gain optimum inverse-turbulent Prandtl number of the flow in curved pipe with upper and lower Re which simulated numerically with CFD. The Re at the inlet side were; Re = 13000 and Re = 63800 on cylindrical curved-pipe with r/D of 1.607.The inverse-turbulent Prandtl number (α) were varied to 1, 1.1, 1.2, 1.3. The curved pipe was an cylindrical air pipe with 43mm inlet diameter. The computational grid that is used for CFD numerical simulation with CFDSOF®, hexagonal-surface fitted consist of 139440 cells. CFD simulation done with inverse-turbulent Prandtl number α varies by 1, 1.1, 1.2, dan 1.3. The wall is assumed to zero-roughness. The CFD simulation generated several results; at Re 13000, the value of α did not affect the turbulent parameter which also confirmed the basic therory of RNG k-ε turbulence model that the minimum Re of α is 2.5 x 104. At Re = 63800, the use of α of 1.1 shows more turbulent flow domination on molecular flow. Lower eddy dissipation by 1.67%, increasing turbulent kinetic energy by 2.2%, and Effective viscosity increase by 4.7% compared to α = 1. Therefore, the use of α 1.1 is the most suitable value to be used to represent turbulent flow in curved pipe with RNG k-ε turbulence model with Re 63800 and r/D 1.607 among others value that have discussed in this paper.
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Hu, Xiao, and Yong Liang Xiong. "Numerical Simulation on Ventilated Cavity Flow with Different Turbulence Models." Applied Mechanics and Materials 368-370 (August 2013): 544–48. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.544.
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The gas leakage and capabilities in cavity tail-part can affect the characteristics of ventilated cavity shape, while turbulence models influence directly the function of turbulence and gas-leakage mode in cavity tail-part. To compare the impact of two turbulent models (large eddy simulation (LES) and Renormalization Group (RNG) k-ε) on ventilated cavity shape, FLUENT6.2 software was used to simulate the three-dimensional ventilated cavity flow, taking into account gravity effects, the cavity transient image and pressure distributions along model surface under two turbulence models were also presented. The results show that the results of LES are more consistent with the transient characteristics of ventilated cavity, and are more suitable for simulations of ventilated cavity flow than RNG k-ε model.
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Jin, Mei, Li Zhan, Guo Xian Yu, Jian Qi Zhang, and Hong Jiao Liu. "Effect of the Flow Models on the Numerical Simulation of Shell and Tube Heat Exchanger." Advanced Materials Research 1008-1009 (August 2014): 910–13. http://dx.doi.org/10.4028/www.scientific.net/amr.1008-1009.910.
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The effect of the volumetric flow rate on the heat transfer of shell and tube heat exchangers was investigated. Furthermore, a comparison of four flow models using for numerical simulation was discussed to provide improved predictions of turbulent flow in the shell and tube heat exchangers. Four flow models tested were Reynolds stress model, k-ε Standard model, k-ε RNG model and k-ε Realizable model, respectively. Multi reference frame technique was used with Fluent software package. During the numerical simulation, the heat dissipation was shown to be strongly dependent on the choice of turbulence model. Compared with the cold model experimental result, k-ε RNG model was a better turbulence model for the prediction of the heat dissipation in the shell and tube heat exchangers among the four models. Furthermore, the good agreement between the numerical results and the experimental result confirmed the validity of the numerical method.
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Velásquez, Laura, Ainhoa Rubio-Clemente, and Edwin Chica. "Numerical and Experimental Analysis of Vortex Profiles in Gravitational Water Vortex Hydraulic Turbines." Energies 17, no. 14 (2024): 3543. http://dx.doi.org/10.3390/en17143543.
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This work compared the suitability of the k-ϵ standard, k-ϵ RNG, k-ω SST, and k-ω standard turbulence models for simulating a gravitational water vortex hydraulic turbine using ANSYS Fluent. This study revealed significant discrepancies between the models, particularly in predicting vortex circulation. While the k-ϵ RNG and standard k-ω models maintained relatively constant circulation values, the k-ϵ standard model exhibited higher values, and the k-ω SST model showed irregular fluctuations. The mass flow rate stabilization also varied, with the k-ϵ RNG, k-ω SST, and k-ω standard models being stabilized around 2.1 kg/s, whereas the k-ϵ standard model fluctuated between 1.9 and 2.1 kg/s. Statistical analyses, including ANOVA and multiple comparison methods, confirmed the significant impact of the turbulence model choice on both the circulation and mass flow rate. Experimental validation further supported the numerical findings by demonstrating that the k-ω shear stress transport (SST) model most closely matched the real vortex profile, followed by the k-ϵ RNG model. The primary contribution of this work is the comprehensive evaluation of these turbulence models, which provide clear guidance on their applicability to gravitational water vortex hydraulic turbine simulations.
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Bayraktar, S., and T. Yilmaz. "Two-dimensional numerical investigation of film cooling by a cool jet injected at various angles for different blowing ratios." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 7 (2008): 1215–24. http://dx.doi.org/10.1243/09544062jmes905.
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This paper presents the thermal and flow characteristics of a cold transverse jet, injected at five different angles (α = 30°, 45°, 60°, 75°, and 90°) into a hot crossflow with four different blowing ratios ( M = 0.1, 0.3, 0.5, and 0.8). Three turbulence models, namely, standard k−∊, renormalization group (RNG) k−∊, and realizable k−∊ are tested for obtaining the accurate turbulence model to predict the effectiveness of film cooling. The tested turbulence models were compared with available experimental data in the literature. The results evinced that the RNG k−∊ turbulence model is the most appropriate among the three. It is also observed that maximum cooling efficiency is obtained at α = 30° and M = 0.8.
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Siswantara, Ahmad Indra, Budiarso та Steven Darmawan. "Investigation of Inverse-Turbulent-Prandtl Number with Four RNG k-ε Turbulence Models on Compressor Discharge Pipe of Bioenergy Micro Gas Turbine". Applied Mechanics and Materials 819 (січень 2016): 392–400. http://dx.doi.org/10.4028/www.scientific.net/amm.819.392.
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Inverse-Turbulent Prandtl number (α) is an important parameter in RNG k-ε turbulence models since it affects the ratio of molecular viscosity and turbulent viscosity. In curved pipe, this highly affects the model prediction to a large range eddy-scale flow. According to Yakhot & Orzag, the α range from 1-1.3929 has not been investigated in detail in curved pipe flow (Yakhot & Orszag, 1986) and specific Re. This paper varied inverse-turbulent Prandtl number α to 1-1.3 in RNG k-ε turbulence model on cylindrical curved pipe in order to obtain the optimum value of α to predict unfully-developed flow in the curve with curve ratio R/D of 1.607. Analysis was conducted numericaly with inlet specified Re of 40900 which was generated from the experiment at α 1, 1.1, 1.2, 1.3. Wall surface roughness is not considered in this paper. With assumption that thermal diffusivity is always dominant to turbulent viscosity, higher Inverse-turbulent Prandtl number represent domination of turbulent viscosity to molecular viscosity of the flow and predict to have more interaction between large scale eddy to small scale eddy as well. The results show the use of α = 1.3 has increased the turbulent kinetic energy by 7% and the turbulent dissipation by 5% compared to general inverse-turbulent Prandtl number of 1. The value difference shows that the use of higher α on RNG turbulence model described more interaction between eddies in secondary and swirling flow at pipe curve at Re = 40900.
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Avramenko, Andrii. "Selecting a k-ε turbulence model for investigating n-decane combustion in a diesel engine combustion chamber". French-Ukrainian Journal of Chemistry 7, № 2 (2019): 80–87. http://dx.doi.org/10.17721/fujcv7i2p80-87.
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The results of a comparative numerical simulation of combustion and formation of toxic substances in a diesel engine combustion chamber are given. Experimental findings were used to identify the mathematical models. The impact of the standard, RNG and realizable k-ε turbulence models on the accuracy of numerical simulation of combustion and the formation of toxic substances was studied. The realizable k-ε turbulence model was shown to provide a closer agreement of computational and experimental data during simulation of the diesel engine process when turbulent flows are described.
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Tanner, F. X., G. S. Zhu, and R. D. Reitz. "A Nonequilibrium Turbulence Dissipation Correction and Its Influence on Pollution Predictions for DI Diesel Engines." Journal of Engineering for Gas Turbines and Power 125, no. 2 (2003): 534–40. http://dx.doi.org/10.1115/1.1501917.
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A correction for the turbulence dissipation rate, based on nonequilibrium turbulence considerations from rapid distortion theory, has been derived and implemented in combination with the RNG k-ε model in a KIVA-based code. This correction reflects the time delay between changes in the turbulent kinetic energy due to changes in the mean flow and its turbulence dissipation rate, and it is shown that this time delay is controlled by the turbulence Reynolds number. The model correction has been validated with experimental data in the compression and expansion phase of a small diesel engine operated in motored mode. Combustion simulations of two heavy-duty DI diesel engines have been performed with the RNG k-ε model and the dissipation rate correction. The focus of these computations has been on the nitric oxide formation and the net soot production. These simulations have been compared with experimental data and their preditions are explained in terms of the turbulence dissipation effect on the transport coefficients for mass and heat diffusion. It has been found, that the dissipation correction yields consistent results with observations reported in previous studies.
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Quaresma, Ana L., Filipe Romão, and António N. Pinheiro. "A Comparative Assessment of Reynolds Averaged Navier–Stokes and Large-Eddy Simulation Models: Choosing the Best for Pool-Type Fishway Flow Simulations." Water 17, no. 5 (2025): 686. https://doi.org/10.3390/w17050686.
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Fishways are an important solution for mitigating the ecological impacts of river barriers, with their hydrodynamics playing a key role in their effectiveness. Computational fluid dynamics (CFD) is now one of the main tools to predict and characterize flow hydrodynamics, but choosing the most suitable turbulence model is considered one of its main challenges. Although substantial research has been carried out on vertical slot fishways, where the flow is predominantly two-dimensional, studies on pool-type fishways with bottom orifices remain scarce. In this study, three Reynolds averaged Navier–Stokes (RANS) turbulence models (the standard k-ε model, the renormalized group k-ε (RNG) model, and the standard k-ω model) and the large-eddy simulation (LES) model performances were compared to simulating the flow in a pool-type fishway with bottom orifices. ADV and PIV experimental data were used to assess model performance. While all the turbulence models accurately predicted the discharges and flow depths, the LES model outperformed the others in reproducing flow patterns, velocities, and turbulent kinetic energy. The RNG model also showed reasonable agreement with the experimental data. By contrast, the k-ε model delivered the poorest performance, failing to accurately predict the sizes of the recirculation zones and the locations of the recirculation axis and presenting the weakest agreement with the experimental observations. The value of the LES model in studying and characterizing fishway hydrodynamics, particularly concerning turbulence parameters, is highlighted.
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Wang, Le, Zhengyu Tian, Hang Yu, Ye Zhang, and Hua Li. "Comparative study on the performance of turbulence models in flow separation of large expansion ratio nozzle." Journal of Physics: Conference Series 2364, no. 1 (2022): 012035. http://dx.doi.org/10.1088/1742-6596/2364/1/012035.
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Abstract The asymmetry of flow separation inside the nozzle with large expansion ratio is the main factor for the generation of side-load in the engine, so the accurate prediction of the flow separation is of great significance. The turbulence model is the key to the prediction, but in different scenarios, the performance of the turbulence model can introduce huge uncertainties. In this paper, a typical thrust-optimized nozzle (VOLVO-S1) is simulated and analyzed for three widely used turbulence models: SST k - ω 、 RNG k - ε and Spalart-Allmaras model. The results show that all these models can effectively predict the mode of shock separation phenomenon. The comprehensive performance of SST k - ω is the best; The Spalart-Allmaras model has better prediction performance under low pressure ratio, and the RNG k - ε model has better prediction effect under high pressure ratio.
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Yuan, A. Hui, Zhen Zhe Li, Tai Hong Cheng, and Yun De Shen. "Effect of Turbulence Model to Simulation Accuracy of Wind Turbine Blade." Applied Mechanics and Materials 397-400 (September 2013): 248–51. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.248.
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With the heightened concern for renewable energy because of significant energy problems, the interest on wind energy has been greatly increased. In this study, 4 kinds of RANS turbulence models were compared and discussed based on developed analysis model. At first, a numerical model for 1kW wind turbine blade was constructed. In the following step, Spalart-Allmaras, standard k-ε, RNG k-ε and Reynolds Stress turbulence models were candidated for comparison. The analysis results show that standard k-ε or RNG k-ε model is relatively good selection under the condition of considering accuracy and computational effort simultaneously. The developed analysis model and simulation results have made a theoretical basis for improving the simulation accuracy of wind turbine blade with minimum computational effort.
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Molchanov, A. M., D. S. Yanyshev, and L. V. Bykov. "Numerical Investigation of a Supersonic Flow in the Near Wake Region of a Cylindrical Afterbody." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 3 (102) (June 2022): 86–95. http://dx.doi.org/10.18698/1812-3368-2022-3-86-95.
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A computational study of a supersonic flow in the base region and the nearest wake of a cylindrical body moving at a supersonic speed have been carried out. A mathematical model of high-enthalpy flows is presented. In this case, the "prehistory" of the flow was taken into account, i.e., the configuration of the computational domain was as close as possible to the real one. The use of various turbulence models for calculating flow in the base region and the nearest wake was analyzed. The following turbulence models were considered: 1) the Spalart --- Allmaras model; 2) SST model; 3) standard k--ε model; 4) k--ε model with compressibility correction; 5) k--ε RNG (renormalized group) model; 6) k--ε Realizable model; 7) standard Reynolds Stress (RS) model; 8) RS BSL (Reynolds stress baseline) model. Based on a comparison of the calculation results with experimental data, it is shown that: 1) when calculating the flow in the base region and in the wake of the vehicle, it is very important to take into account the "prehistory" of the flow, i.e., to calculate the flow around the entire vehicle; 2) the best match was obtained using Reynolds Stress models and the k--ε RNG model
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El-Behery, Samy M., Gamal H. Badawy, and Fathi M. Mahfouz. "Three-Dimensional Simulation of Decaying Turbulent Swirling Flow Using Different Turbulence Models." International Journal of Heat and Technology 40, no. 1 (2022): 211–18. http://dx.doi.org/10.18280/ijht.400125.
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This paper presents a numerical study of the turbulent swirling flow in a horizontal tangential inlet tube. The commercial CFD code ANSYS FLUENT 15 was used for solving the set of governing equations using different turbulence models. Eight turbulence models are tested which are, standard k–ε, realizable k–ε, RNG k–ε, SST k–ω, Non-Linear k–ε, v2-f, RSM (Quadratic Pressure-Strain Model), and RSM (Stress-Omega Model). All these turbulence models are available directly in the ANSYS FLUENT except the non-linear k–ε which was implemented in the solver using User Defined Functions (UDF). The numerical predictions are compared with experimental measurements from literature for tangential, axial velocity profiles and Reynolds stresses profiles within the tested tube. The results indicated that the axial velocity is predicted fairly well by the standard k–ε model while the tangential velocity is well predicted by RSM. On the other hand, v2-f model predicts the Reynolds stresses better than the other tested models. The statistical analysis of turbulence model performance showed that, the RSM (Quadratic Pressure-Strain) model gives the best agreement with all data of experiments followed by non-linear k–ε and standard k–ε turbulence models.
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Zhu, WenRuo, ZhongXin Gao, YongJun Tang, JianGuang Zhang, and Li Lu. "Adaptability of turbulence models to predict the performance and blade surface pressure prediction of a Francis turbine." Engineering Computations 33, no. 1 (2016): 238–51. http://dx.doi.org/10.1108/ec-06-2014-0137.
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Purpose – The purpose of this paper is to analyze the ability of turbulence models to model the flow field in the runner of a Francis turbine. Although the complex flow in the turbine can be simulated by CFD models, the prediction accuracy still needs to be improved. The choice of the turbulence model is one key tool that affects the prediction accuracy of numerical simulations. Design/methodology/approach – This study used the SST k-w and RNG k-e turbulence models, which can both accurately predict complex flow fields in numerical simulations, to simulate the flow in the entire flow passage of a Francis turbine with the results compared against experimental data for the performance and blade pressure distribution in the turbine to evaluate the applicability of the turbulence models. Findings – The results show that the SST k-w turbulence model more accurately predicts the turbine performance than the RNG turbulence model. However, the blade surface pressures predicted by the SST k-w turbulence model were basically identical to those predicted by the RNG k-e turbulence model, with both accurately predicting the experimental data. Research limitations/implications – Due to the lack of space, the method used to measure the blade surface pressure distributions is not introduced in this paper. Practical implications – Turbine performance and flow field pressure in the runner, which are the basis of turbine preliminary performance judgment and optimization through CFD, can be used to judge the rationality of the turbine runner design. The paper provides an evidence for the turbulence selection in numerical simulation to predict turbine performance and flow field pressure in the runner and improves the CFD prediction accuracy. Originality/value – This paper fulfils a test of the flow field pressure in the runner, which provide an evidence for judge the adaptability of turbulence model on the flow field in runner. And this paper also provides important evaluations of two turbulence models for modeling the flow field pressure distribution in the runner of a Francis turbine to improve the accuracy of CFD models for predicting turbine performance.
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Souid, Anouar, Wassim Kriaa, Hatem Mhiri, Georges Le Palec, and Philippe Bournot. "Numerical Simulation of a Ceramic Furnace Burner - Capacity of Turbulent and Radiation Models." Defect and Diffusion Forum 283-286 (March 2009): 243–49. http://dx.doi.org/10.4028/www.scientific.net/ddf.283-286.243.
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We intend in this work to model an industrial burner replica of the ceramic tunnel furnace of the Ceramics Modern Society (SOMOCER, TUNISIA). This study aims to evaluate the ability of turbulence and radiation models to predict the dynamics and heat transfer fields. The study is conducted by means of numerical simulations in presence of a reactive flow using the commercial code FLUENT. The 3D Navier-Stokes equations and four species transport equations are solved with the eddy-dissipation (ED) combustion model. We use three turbulence models (k- standard, k- RNG, and RSM) and two radiation models (DTRM and DO). The obtained results demonstrate that the k- standard turbulence model is unable to predict the flow characteristics whereas; the k- RNG and RSM models give a satisfying agreement with the experiments. Suitable results are provided by the DTRM radiation model; whereas, those given by the DO model can be improved.
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Yin, Yuan, Yangsen Li, Ruizong Lin, et al. "Research on turbulence model for simulation of wind flow in mountain areas of micro-topography." Journal of Physics: Conference Series 2441, no. 1 (2023): 012012. http://dx.doi.org/10.1088/1742-6596/2441/1/012012.
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Abstract The accuracy of wind flow simulation in mountain area in micro-topography is related to discrete scheme, turbulence model and wall function. In this paper, the standard hill model is adopt to analyze the calculation accuracy of different turbulence models. Four turbulence models, including RNG k-ε, k-ω, SST k-ω and TSST k-ω, were used in the calculation, and were compared with the result of wind tunnel test. The calculation results with the second-order upwind scheme, the SST or TSST turbulence model and the scalable wall function are basically consistent with results of wind tunnel test.
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Varghese, Sonu S., and Steven H. Frankel. "Numerical Modeling of Pulsatile Turbulent Flow in Stenotic Vessels." Journal of Biomechanical Engineering 125, no. 4 (2003): 445–60. http://dx.doi.org/10.1115/1.1589774.
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Pulsatile turbulent flow in stenotic vessels has been numerically modeled using the Reynolds-averaged Navier-Stokes equation approach. The commercially available computational fluid dynamics code (CFD), FLUENT, has been used for these studies. Two different experiments were modeled involving pulsatile flow through axisymmetric stenoses. Four different turbulence models were employed to study their influence on the results. It was found that the low Reynolds number k-ω turbulence model was in much better agreement with previous experimental measurements than both the low and high Reynolds number versions of the RNG (renormalization-group theory) k-ε turbulence model and the standard k-ε model, with regard to predicting the mean flow distal to the stenosis including aspects of the vortex shedding process and the turbulent flow field. All models predicted a wall shear stress peak at the throat of the stenosis with minimum values observed distal to the stenosis where flow separation occurred.
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Sarmin, Shahliza Azreen, Azli Abd Razak, Fauziah Jerai, and Mohd Khir Harun. "CFD SIMULATION AND VALIDATION FOR MIXING VENTILATION SCALED-DOWN EMPTY AIRCRAFT CABIN USING OPENFOAM." Jurnal Teknologi 85, no. 5 (2023): 191–200. http://dx.doi.org/10.11113/jurnalteknologi.v85.19423.
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An investigation into the spread of the COVID-19 virus within a confined space including an aircraft cabin is essential in order to find out the mechanism. However, this is time-consuming and limited in scope, so a computational fluid dynamics (CFD) simulation is used instead. Therefore, a prior study and an appropriate choice of turbulence model are required before the simulation. The main objective of this study is to validate and evaluate the results predicted by the Open Source Field Operation and Manipulation (OpenFOAM) software through comparison with the experimental data from the literature which was conducted using particle image velocimetry (PIV) measurement. Three different Reynolds-averaged Navier-Stokes turbulence models were selected; Re-normalisation Group k - ɛ (RNG), Realizable k - ɛ (RLZ) and Low Reynold Number (LRN) to simulate a mixing ventilation system of a scaled-down model of empty aircraft cabin. In the RNG and LRN model cases, a fairly large circulation flows were observed on the right and left sides of the model representing the passenger area. The results were also evaluated quantitatively using the factor of two of observations (FAC2) for the velocity components and turbulent kinetic energy (TKE) with root mean square error (RMSE) for the former and normalised mean square errors (NMSE) for the latter. The simulation results showed that RNG and LRN are capable of predicting the flow field well. However, for TKE prediction LRN performed better than RNG which concluded that LRN is the suitable turbulence model in simulating flow fields in investigated case.
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Marco, Andrés Guevara-Luna, and Carlos Belalcázar-Cerón Luis. "NGL supersonic separator: modeling, improvement, and validation and adjustment of k-epsilon RNG modified for swirl flow turbulence model." Revista Facultad de Ingeniería -redin-, no. 82 (March 16, 2017): 82–93. https://doi.org/10.17533/udea.redin.n82a11.
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The processing of natural gas requires the implementation of new technologies in a context of increasing demand around the world. The natural gas liquids (NGL) separation using supersonic devices is a novel and efficient way to reduce volume of installed equipment and operation costs using the effects of highly turbulent and circular flows. This research implemented Computational Fluid Dynamics (CFD) modeling to improve the efficiency of typical NGL recovery process using the supersonic approach. In this research, a novel turbulence modeling approach was implemented aiming to minimize the processing time, and the results obtained were validated with experimental data available. This research is based on the model called k-epsilon RNG modified for swirl flow, this model has not been used and validated previously in highly compressible, turbulent and circular flow systems. The efficiency of the process was improved by 11% in comparison to the efficiency reported in past studies, and the processing time for the modeling was reduced by 40% with the proposed and adjusted turbulence approach. During the validation of the model k-epsilon RNG modified for swirl flow the swirl factor, part of the turbulence model, was adjusted to an optimum value for compressible, turbulent and circular flow systems involved in supersonic NGL separation process, allowing accurate results to be obtained with lower processing time than with other typical and common approaches as RSM and LES.
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Molchanov, A. M., and M. V. Siluyanova. "Numerical investigation of a near-wake flowfield with base bleed." Journal of Physics: Conference Series 2308, no. 1 (2022): 012011. http://dx.doi.org/10.1088/1742-6596/2308/1/012011.
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Abstract A computational study of a supersonic flow in the base region and the nearest wake of a cylindrical body moving at a supersonic speed has been carried out. In this case, the “prehistory” of the flow was taken into account, i.e. the configuration of the computational domain was as close as possible to the real one. The use of various RANS turbulence models for calculating flow in the base region and the nearest wake was analyzed. The following turbulence models were considered: 1) SST model; 2) Standard k–ε model; 3) k–ε RNG model; 4) Standard Reynolds Stress (RS) model; 5) RS BSL model. Based on a comparison of the calculation results with experimental data, it is shown that: 1) when calculating the flow in the base region and in the wake of the vehicle, it is very important to take into account the “prehistory” of the flow, i.e. to calculate the flow around the entire vehicle; 2) the best match was obtained using the the k–ε RNG model. The effect of base bleed on the near-wake flowfield of a cylindrical afterbody aligned with a Mach 2.5 flow has been investigated.
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Candra Damis Widiawaty, Ahmad Indra Siswantara, Gun Gun R Gunadi та ін. "Optimization of inverse-Prandtl of Dissipation in standard k-ε Turbulence Model for Predicting Flow Field of Crossflow Turbine". CFD Letters 14, № 1 (2022): 112–27. http://dx.doi.org/10.37934/cfdl.14.1.112127.
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Despite the successful use of the Standard model in simulating turbulent flow for many industrially relevant flows, the model is still less accurate for a range of important problems, such as unconfined flows, curved boundary layers, rotating flows, and recirculating flows. As part of the authors’ effort to extend the model applicability and reliability, this paper aims to study the effects of diffusivity parameter called the turbulent Prandtl number of dissipation rate () on the Standard model performance for predicting recirculating flow in a crossflow water turbine. The value of this parameter was varied from 0.5 to 1.5 in the CFD simulations, and the results were compared to the more sophisticated model, namely the RNG , which has been first qualitatively validated by an experimental result. In addition, the parameter value was also adjusted using the Multi-Linear Regression (MLR) method ranging from 0.42 to 1.5 to complement the CFD simulations. It was observed that reducing the value is effective in minimizing the average deviation of the turbulence properties concerning the RNG model. However, the adjusted model still faces difficulty in accurately predicting the pressure and velocity field. Based on this result, adjusting the constant in the Standard turbulence model has the potential to improve the model performance for modelling recirculating flow in terms of the turbulence properties, but still needs further investigation for the flow properties.
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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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Radomsky, R. W., and K. A. Thole. "Measurements and Predictions of a Highly Turbulent Flowfield in a Turbine Vane Passage." Journal of Fluids Engineering 122, no. 4 (2000): 666–76. http://dx.doi.org/10.1115/1.1313244.
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As highly turbulent flow passes through downstream airfoil passages in a gas turbine engine, it is subjected to a complex geometry designed to accelerate and turn the flow. This acceleration and streamline curvature subject the turbulent flow to high mean flow strains. This paper presents both experimental measurements and computational predictions for highly turbulent flow as it progresses through a passage of a gas turbine stator vane. Three-component velocity fields at the vane midspan were measured for inlet turbulence levels of 0.6%, 10%, and 19.5%. The turbulent kinetic energy increased through the passage by 130% for the 10% inlet turbulence and, because the dissipation rate was higher for the 19.5% inlet turbulence, the turbulent kinetic energy increased by only 31%. With a mean flow acceleration of five through the passage, the exiting local turbulence levels were 3% and 6% for the respective 10% and 19.5% inlet turbulence levels. Computational RANS predictions were compared with the measurements using four different turbulence models including the k-ε, Renormalization Group (RNG) k-ε, realizable k-ε, and Reynolds stress model. The results indicate that the predictions using the Reynolds stress model most closely agreed with the measurements as compared with the other turbulence models with better agreement for the 10% case than the 19.5% case. [S0098-2202(00)00804-X]
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Adanta, Dendy, Dewi Puspita Sari, Nura Muaz Muhammad, and Aji Putro Prakoso. "HISTORY OF UTILIZATION OF THE COMPUTATIONAL FLUID DYNAMICS METHOD FOR STUDY PICO HYDRO TYPE CROSS-FLOW." Indonesian Journal of Engineering and Science 2, no. 1 (2021): 017–24. http://dx.doi.org/10.51630/ijes.v2i1.11.
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Energy crisis in particular, electricity in the isolated rural areas of Indonesia is a very crucial issue that needs to be resolve through electrification . Compared to other options, pico hydro cross-flow turbine (CFT) is the better option to provides electrical power for the isolated rural areas. Studies to improve CFT performance can be undertaken analytically, numerically, experimentally, or a combination of those methods. However, the development of computer technology makes numerical simulation studies have become increasingly frequent. This paper describes the utilization of the computational fluid dynamic (CFD) approach in the pico hydro CFT method. This review has resulted that the recommended Renormalization Group (RNG) k-ε turbulence model for CFT CFD simulation because its absolute relative error is lower than standard k-ε and transitional Shear Stress Transport (SST). The absolute relative error for the RNG k-ε turbulence model of 3.08%, standard k-ε of 3.19%, and transitional SST of 3.10%. While for the unsteady approach, the six-degrees of freedom (6-DoF) are considered because more accurate than moving mesh. The absolute relative error for 6-DoF of 3.1% and moving mesh of 9.5%. Thus, based on the review, the RNG k-ε turbulence model and 6-DoF are proposed for the pico hydro CFT CFD study.
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Azizi, Hossein, Reza Saleh, Mohsen Kahrom, and Reza Andalibi. "Numerical simulation of different turbulence models aiming at perdicting the flow and temperature separation in a Ranque-Hilsch vortex tube." Thermal Science 18, no. 4 (2014): 1159–71. http://dx.doi.org/10.2298/tsci110727201a.
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A computational fluid dynamics (CFD) model is used to compare the effect of different Reynolds Averaged Navier-Stokes (RANS) based turbulence models in predicting the temperature separation and power separation in a Ranque-Hilsch vortex tube. Three first order turbulence models (standard k-?, Renormalized group RNG and shear stress transport (SST) K-? model) together with a second order numerical scheme are surveyed in the present work. The simulations are done in 2D steady, axisymetric with high swirl flow model. The performance curves (hot and cold outlet temperatures and power separation versus hot outlet mass fraction) obtained by using these turbulence models are compared with the experimental results in different cold mass fractions. The aim is to select an appropriate turbulence model for the simulation of the flow phenomena. Because of large discrepancy between 2D and experiment, validation in 3D model is also considered. The performance analysis shows that among all the turbulence models investigated in this study, temperature separation predicted by the Renormalized group RNG model is closer to the experimental results.
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Danilenkaitė, Justina, Aleksandras Chlebnikovas, and Petras Vaitiekūnas. "MATHEMATICAL MODEL OF THE MULTI-CHANNEL SPIRAL CYCLONE / DAUGIAKANALIO SPIRALINIO CIKLONO ORO GREIČIŲ TYRIMAS." Mokslas - Lietuvos ateitis 5, no. 4 (2013): 349–55. http://dx.doi.org/10.3846/mla.2013.56.
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The article deals with a problem of experimental investigation and numerical simulation of gas aerodynamics of a multi-channel spiral cyclone with a tangential inlet. The paper presents an overview of experimental and theoretical works on the cyclones having a particularly complex turbulent flow and focuses on three-dimensional transport differential equations for a non-compressible laminar and turbulent flow inside the cyclone. The equations have been solved applying the numerical finite volume method using the RNG (Re–Normalisation Group) k-ε turbulence model. The numerical simulation of the flow cyclone has been carried out. The height of the cyclone is 0.80 m with 0.33 m in diameter, the height of the spiral–cylindrical part – 0.098 meters and that of the cone – 0.45 m. Inlet dimensions (cylindrical part on the side), in accordance with drawings makes a×b = 28×95 mm. The mathematical model for the air traffic movement cyclone has accounted for Navier-Stokes (Reynolds) three-dimensional differential equations. The simulation results have been obtained with reference to the cyclone of tangential velocity profiles using RNG k-ε turbulence model. The inlet velocity of 5.1 m/s slightly differs from experimental results, thus making an error of 7%. Article in Lithuanian. Santrauka Nagrinėjama dujų aerodinamikos daugiakanaliame spiraliniame ciklone eksperimentinio tyrimo ir skaitinio modeliavimo problema. Apžvelgti eksperimentiniai ir teoriniai ciklonų, kuriuose susidaro ypač sudėtingas sūkurinis srautas, tyrimai. Pateiktos nespūdžiojo laminarinio ir turbulentinio srauto tekėjimo ciklono viduje diferencialinės trimatės pernašos lygtys. Jos skaitiškai spręstos baigtinių tūrių metodu taikant RNG (Re – Normalisation Group) k–ε turbulencijos modelį. Atliktas skaitinis oro srauto judėjimo ciklone modeliavimas. Ciklono aukštis 0,80 m, skersmuo 0,33 m, spiralinės-cilindrinės dalies aukštis 0,098 m, kūginės – 0,45 m, įtekėjimo angos matmenys (cilindrinės dalies šone) pagal brėžinius yra a×b = 28×95 mm. Oro srauto judėjimo ciklone matematinį modelį sudaro Navjė ir Stokso (Reinoldso) trimačių diferencialinių lygčių sistema. Modeliavimo rezultatai, t. y. taikant RNG k–ε turbulencijos modelį (įtekėjimo greitis 5,1 m/s) gauti tangentinio greičio ciklone kitimo duomenys, nežymiai (su 7 % paklaida) skyrėsi nuo eksperimentinių rezultatų.
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Hajivand, Masoud. "High-Fidelity RANS CFD Simulations of Physico-Chemical Process of Combustion in Gas Turbine Combustion Chambers in ANSYS CFX." Energy engineering and control systems 10, no. 2 (2024): 81–95. https://doi.org/10.23939/jeecs2024.02.081.
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This study examines the validation and precision of essential parameters, including temperature distribution and nitrogen oxide (NOx) emissions, at the outlet of a gas turbine combustion chamber through high-fidelity Reynolds-Averaged Navier-Stokes (RANS) CFD simulations. The propane(C3H8)-air combustion process is modeled in ANSYS CFX utilizing three various turbulence models, including standard k-ε, RNG k-ε, and shear stress transport (SST), beside various combustion models such as the Eddy Dissipation Model (EDM), a hybrid of Eddy Dissipation and Finite Rate Chemistry (EDM/FRC), and the Flamelet model, including the P-1 model of radiation. A thorough sensitivity analysis was performed utilizing fine, medium, and coarse unstructured computational meshes to improve the reliability and accuracy of the results. The obtained CFD results showed that for outlet temperature, the standard k-ε turbulence model coupled with the Flamelet combustion model yields a mean deviation of -6.8%, while k-ε coupled with EDM yields a mean deviation of -9.9%. It also gave the lowest deviation of NOx emissions at combustor outlet equal to 2.3% when EDM/FRC combustion model was used in tandem with SST turbulence model. While the same combustion model coupled with the standard k-ε and RNG k-ε turbulence models exhibited a higher mean deviation of 13.6% and 15.4%, respectively, in predicting NOx emissions.
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Wang, Liu, Wang, Zhou, Jiang, and Li. "Numerical Simulation of the Sound Field of a Five-Stage Centrifugal Pump with Different Turbulence Models." Water 11, no. 9 (2019): 1777. http://dx.doi.org/10.3390/w11091777.
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To study the influence of the turbulence model on the sound field of pumps, the standard k-ε, Re-normalization Group (RNG) k-ε and Shear Stress Transfer (SST) k-ω models were employed to simulate flow and sound fields of a five-stage centrifugal pump with a vaned-diffuser. The vibration characteristics of the pump were simulated with the modal response method. A vibration experiment in the pump was carried out to verify the feasibility of the numerical simulation of the hydrodynamic noise in the pump. Results show that in the spectrum of internal and external noise, the peak value appears at axial passing frequency (APF) and its harmonic frequency. Compared with the standard k-ε model, the RNG k-ε and SST k-ω models show good consistence with the noise characteristics of experimental results, indicating the characteristic frequency and revealing the approximate behavior of the sound field in the pump. In general, the simulation of the sound field based on the RNG k-ε model is most appropriate for the multistage centrifugal pump with a vaned-diffuser.
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Hosseini, Seyyed Hossein, Seyyed Mohammad Javadi, and Ehsan Ebrahimnia-Bajestan. "Turbulent Convective Heat Transfer of Nanofluids." Applied Mechanics and Materials 110-116 (October 2011): 3873–77. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.3873.
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In this paper, the convective heat transfer of nanofluid flow in a turbulent boundary layer of a flat plate is simulated numerically. Turbulent flow equations with RNG K-ε turbulence model are solved employing Fluent software. Furthermore, the effects of nanoparticle concentration on the heat transfer characteristics are studied. The results show that nanofluids enhance the heat transfer coefficient dramatically with little change in pressure drop.
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Marzouk, Osama, and E. David Huckaby. "Simulation of a Swirling Gas-Particle Flow Using Different k-epsilon Models and Particle-Parcel Relationships." Engineering Letters 18, no. 1 (2010): 7. https://doi.org/10.5281/zenodo.14591654.
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We performed several numerical simulations of a co-axial particle-laden swirling air flow in a vertical circular pipe. The air flow is modeled using the unsteady Favre-averaged Navier-Stokes equations. A Lagrangian model is used for the particle motion. The results of the simulations using three versions of the k−epsilon turbulence model (standard, re-normalization group - RNG, and realizable) are compared with experimental mean velocity profiles. The standard model achieved the best overall performance. The realizable model was unable to satisfactorily predict the radial velocity; it is also the most computationally-expensive model. The simulations using the RNG model predicted extra recirculation zones. We also compared the particle and parcel approaches in solving the particle motion. In the latter, multiple similar particles are grouped in a single parcel, thereby reducing the amount of computation.
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Saru, Muhsine, Hıfzı Arda Erşan, and Erhan Pulat. "The Effect of Turbulent Intensity on Friction Coefficient in Boundary-Layer Transitional Flat Plate Flow." Applied Sciences 15, no. 11 (2025): 5852. https://doi.org/10.3390/app15115852.
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In this study, the effect of inlet-turbulence intensity on the friction coefficient for the transitional boundary layer has been investigated computationally. For this purpose, two equation turbulence models of Std. k-ε, RNG k-ε, Std. k-ω, and SST k-ω have been compared with the Gamma–Theta (GT) transitional model, and it has been found that the Gamma–Theta model is the most consistent model with the experimental values of the ERCOFTAC T3A test case. Then, the effect of inlet-turbulence intensity on the friction coefficient has been computed by using this Gamma–Theta model. The transition from laminar to turbulence is shortened with increasing turbulence intensity by changing it from 1% to 10%. The most suitable inlet-turbulence intensity value with the experimental results of the ERCOFTAC T3A test case is found as Tu = 3.3%.
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Wu, Jian Feng, Cai Hua Wang, and Yan Chao Zhao. "The Turbulent Flow Model Selection for Numerical Wind Tunnel Simulation of the Low Layer Double Slope Roof." Applied Mechanics and Materials 204-208 (October 2012): 4892–95. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.4892.
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Using the FLUENT software, this paper taking the current code for the design of building structures as the comparison standard, have numerical wind tunnel simulation of the wind the surface wind pressure on low layer double slope roof. It focuses on the analysis of the effects of turbulence model selection on the numerical simulation results, such as Spalart-Allmaras、Standard k −ε、RNG k −ε、Realizable k −ε、Standard k −ω、SST k −ω and RSM, to provide a basis for the reasonable selection of turbulence models.
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Nouhaila, Ouyoussef, Moustabchir Hassane, Maria Luminita Scutaru, and Liviu Jelenschi. "On the Accuracy of Turbulence Model Simulations of the Exhaust Manifold." Applied Sciences 14, no. 12 (2024): 5262. http://dx.doi.org/10.3390/app14125262.
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This study investigating the accuracy of turbulence model simulations of the exhaust manifold using computational fluid dynamics (CFD) carries significant implications. By modeling and analyzing the flow of emissions, we aim to identify areas of high stress and pressure, minimize the pressure drop, and maximize the flow of exhaust gases. This not only enhances engine performance, reduces emissions, and improves the durability of the manifold but also provides a unique opportunity to predict and analyze the flow and performance of the exhaust manifold, both quantitatively and qualitatively. This paper aims to provide a detailed comparison of five turbulence models that are commonly used in CFD to offer valuable insights into their accuracy and reliability in predicting the flow characteristics of exhaust gases. The results show that the k-kl-ω model showed the highest maximum velocity and the most comprehensive temperature range, efficiently capturing the transitional flow effects. The K-ω STD and SST transition models displayed significantly higher turbulent kinetic energy (TKE) values, indicating their enhanced effectiveness in modeling complex turbulent and transitional flows. Conversely, the Reynolds stress and RNG k-epsilon models displayed lower TKE values, suggesting more subdued turbulence predictions. Despite this, all models exhibited similar pressure drop trends, with a noticeable increase near the midpoint of the manifold. These quantitative findings provide valuable insights into the suitability of different turbulence models for optimizing exhaust manifold design.
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Banks, J., and N. W. Bressloff. "Turbulence Modeling in Three-Dimensional Stenosed Arterial Bifurcations." Journal of Biomechanical Engineering 129, no. 1 (2006): 40–50. http://dx.doi.org/10.1115/1.2401182.
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Under normal healthy conditions, blood flow in the carotid artery bifurcation is laminar. However, in the presence of a stenosis, the flow can become turbulent at the higher Reynolds numbers during systole. There is growing consensus that the transitional k−ω model is the best suited Reynolds averaged turbulence model for such flows. Further confirmation of this opinion is presented here by a comparison with the RNG k−ϵ model for the flow through a straight, nonbifurcating tube. Unlike similar validation studies elsewhere, no assumptions are made about the inlet profile since the full length of the experimental tube is simulated. Additionally, variations in the inflow turbulence quantities are shown to have no noticeable affect on downstream turbulence intensity, turbulent viscosity, or velocity in the k−ϵ model, whereas the velocity profiles in the transitional k−ω model show some differences due to large variations in the downstream turbulence quantities. Following this validation study, the transitional k−ω model is applied in a three-dimensional parametrically defined computer model of the carotid artery bifurcation in which the sinus bulb is manipulated to produce mild, moderate, and severe stenosis. The parametric geometry definition facilitates a powerful means for investigating the effect of local shape variation while keeping the global shape fixed. While turbulence levels are generally low in all cases considered, the mild stenosis model produces higher levels of turbulent viscosity and this is linked to relatively high values of turbulent kinetic energy and low values of the specific dissipation rate. The severe stenosis model displays stronger recirculation in the flow field with higher values of vorticity, helicity, and negative wall shear stress. The mild and moderate stenosis configurations produce similar lower levels of vorticity and helicity.
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Zhou, Shao Ping, Pei Wen Lv, Xiao Xia Ding, Yong Sheng Su, and De Quan Chen. "Numerical Simulation and Impeller Optimization of a Centrifugal Pump." Advanced Materials Research 472-475 (February 2012): 2195–98. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.2195.
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The three-dimensional flow field simulation of a centrifugal pump was presented by using commercial CFD code. In order to study the most suitable turbulence model, the three known turbulence models of Standard k-ε, RNG k-ε, Realizable k-ε were applied to simulate the flow field of the MJ125-100 centrifugal pump and predict the performance of the pump. The simulation results of head and efficiency were compared with available experimental data, and the comparison showed that the result of the numerical simulation by RNG k-ε model had the best agreement. Additionally, the effect of number of blades on the efficiency of pump was studied. The number of blades was changed from 4 to 7. The results showed that the impeller with 7 blades had the highest efficiency.
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Karim, M. M., N. Mostafa, and M. M. A. Sarker. "Numerical study of unsteady flow around a cavitating hydrofoil." Journal of Naval Architecture and Marine Engineering 7, no. 2 (2011): 51–60. http://dx.doi.org/10.3329/jname.v7i2.5270.
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This paper presents a numerical study of the non-cavitating and cavitating flow around CAV 2003 hydrofoil. The phenomenon of cavitation is modeled through a mixture model. For the numerical solution of cavitating flow a bubble dynamics cavitation model is used to describe the generation and evaporation of vapor phase. The non-cavitating study focuses on the influence of the turbulence model and different mesh sizes used in the computation. Three turbulence models such as Spalart-Allmaras, Shear Stress Turbulence (SST) k-? model, RNG k-? with enhanced wall treatment are used to capture turbulent boundary layer along the hydrofoil surface. The results predicted by these models are compared with each other. The cavitating study first presented an unsteady behavior of the partial cavity attached to the foil. Then, an analysis of a supercavitating condition is performed. The predicted results show good agreement with results published by other researchers.DOI: 10.3329/jname.v7i2.5270
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Amorim, Felipe Grossi L., Jean Helder M. Ribeiro, Marília Gabriela J. Vaz, and Ramon Molina Valle. "Sensitivity Analysis of the Air Flow inside a Single Cylinder Engine for Different Turbulence Models Using CFD." Advanced Materials Research 1016 (August 2014): 624–29. http://dx.doi.org/10.4028/www.scientific.net/amr.1016.624.
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Theincrease of greenhouse gases emissions makes necessary to improve the comprehension of the Internal Combustion Engines operation. One of the factors that affect the combustion in these engines is the turbulence, since it can raise the quality of the fuel-air mixture inside the combustion chamber. However, when modeling internal combustion engines using CFD, the turbulence model choice is always a relevant problem. The present paper analyzes the results for three different turbulence models (k-ε Realizable, RNG k-ε and Menter k-ω SST) ina single-cylinder engine geometry, comparing numerical and experimental pressure data. For this experiment, the k-ε models obtained more trustable results than the k-ω SST, using less computational resources. The models achieved good results for eddy recirculation inside de cylinder and in regions of free shear flow at the valve openings, which makes possible to observe the correlation between parameters such as tumble and turbulent kinetic energy.
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Zhang, Ying, Longtao Wang, Angui Li, and Pengfei Tao. "Performance evaluation by computational fluid dynamics modelling of the heavy gas dispersion with a low Froude number in a built environment." Indoor and Built Environment 29, no. 5 (2019): 656–70. http://dx.doi.org/10.1177/1420326x19856041.
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To evaluate the dispersion of a heavy gas, such as sulphur hexafluoride, with a low Froude number in a built environment, an experimental and numerical simulation study was conducted. The experiment was carried out using seven different injection inlet configurations in an experimental chamber. The release rate was found to have a great effect on the concentration in the lower part of the chamber. The obstacle in the middle of the chamber could cause a non-uniform distribution of concentration, particularly due to variations in locations and angles of the release outlets. Additionally, numerical simulations were carried out to evaluate four turbulence models: the standard k- ε model, the realizable k- ε model, the re-normalization group (RNG) k- ε model and the shear stress transport (SST) k-ω model. Four indicators were used to evaluate the turbulent model performance. In general, the SST k-ω model performed the best, with geometric mean bias ( MG) = 0.968 and geometric variance ( VG) = 1.09 at 0.055 m height, and with MG = 0.384 and VG = 2.80 at 0.6 m height. The standard k- ε model was the next best in performance, followed by the realizable k- ε and the RNG k- ε model.
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Wang, Jing Yu, та Xing Jun Hu. "Application of RNG k-ε Turbulence Model on Numerical Simulation in Vehicle External Flow Field". Applied Mechanics and Materials 170-173 (травень 2012): 3324–28. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.3324.
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The two turbulence models were used to numerically simulate the external flow field around the Ahmed standard car model, and the aerodynamic drag and lift coefficients and aerodynamic characteristics around model were obtained. By comparison between the simulation results and the corresponding wind tunnel test data, the differences of two turbulence models were analyzed. The results indicated the simulation result of RNG k-εturbulence model is more precision, and it is more suitable on numerical simulation in vehicle external flow field. The conclusions provide reference for how to select turbulence model.
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Vaitiekūnas, Petras, Egidijus Petraitis, Albertas Venslovas, and Aleksandras Chlebnikovas. "AIR STREAM VELOCITY MODELLING IN MULTICHANNEL SPIRAL CYCLONE SEPARATOR." JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT 22, no. 3 (2014): 183–93. http://dx.doi.org/10.3846/16486897.2014.931283.
Full textAbstract:
Numerical modelling problem is investigated in a gas aerodynamics multichannel spiral cyclone separator with a tangential inflow. Experimental and theoretical papers analysing cyclone separator with particularly complex turbulent flow were reviewed. The three-dimensional transport differential equations for incompressible laminar and turbulent flow inside the cyclone separator were presented. They were numerically solved by finite volume method using the Re-Normalisation Group (hereinafter RNG) k-ε turbulence model. The numerical air flow movement was modelled in cyclone separator with the following dimensions: 0.95 m height, 0.330 m diameter, 0.88 m height of spiral-cylindrical part, 0.39 m height of conical part, inflow dimensions (on the side of cylindrical part) according to the drawings were a × b = 28 × 95 mm. The mathematical model of air flow movement in cyclone separator was composed by Navier-Stokes (Reynolds) as the three-dimensional differential equation system. The modelling results were obtained by the tangential and axial velocity profiles in cyclone separator using RNG k-ε turbulence model, the inflow velocity from 4.1 m/s to 15.4 m/s coincided well with the experimental results. This is the first article testing for multichannel cyclone and determined distributions of aerodynamic parameters. The absolute error between experimental and modelling results changed from 0.01 to 0.24 units.
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Tolentino, San, Jorge Mírez, and Omar González. "Evaluation of turbulence models for incompressible flow in a venturi tube." FME Transactions 52, no. 4 (2024): 534–43. http://dx.doi.org/10.5937/fme2404534t.
Full textAbstract:
Turbulence models are semi-empirical transport equations that model flow behavior. They are compared on a recurring basis to know which of them presents the best fit with experimental data for different laboratory equipment. In the present work, the incompressible flow field (water) is simulated with the computational fluid dynamics (CFD) tool and RANS model for the geometry of a Venturi tube in 2D computational domains, with the objective of evaluating six turbulence models: standard k-e, RNG k-e, standard k-o, SST k-o, RSM and SA. The numerical results of the trajectories of the pressure pattern curves at the walls and axial symmetry are close to each other. Pressure drops occur at the throat. The percentage errors of the turbulence models increase as the magnitude of the pressure ratio increases, for r p =1.0932, r p =1.1118, r p =1.1377, and r p =1.1531. It is concluded that the SA turbulence model of Spalart-Allmaras (1992) best fits the experimental pressure data, with percentage errors of less than 10%.
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Dehdarinejad, Ehsan, Morteza Bayareh, and Mahmud Ashrafizaadeh. "A numerical study on combined baffles quick-separation device." International Journal of Chemical Reactor Engineering 19, no. 5 (2021): 515–26. http://dx.doi.org/10.1515/ijcre-2021-0007.
Full textAbstract:
Abstract The transfer of particles in laminar and turbulent flows has many applications in combustion systems, biological, environmental, nanotechnology. In the present study, a Combined Baffles Quick-Separation Device (CBQSD) is simulated numerically using the Eulerian-Lagrangian method and different turbulence models of RNG k-ε, k-ω, and RSM for 1–140 μm particles. A two-way coupling technique is employed to solve the particles’ flow. The effect of inlet flow velocity, the diameter of the splitter plane, and solid particles’ flow rate on the separation efficiency of the device is examined. The results demonstrate that the RSM turbulence model provides more appropriate results compared to RNG k-ε and k-ω models. Four thousand two hundred particles with the size distribution of 1–140 µm enter the device and 3820 particles are trapped and 380 particles leave the device. The efficiency for particles with a diameter greater than 28 µm is 100%. The complete separation of 22–28 μm particles occurs for flow rates of 10–23.5 g/s, respectively. The results reveal that the separation efficiency increases by increasing the inlet velocity, the device diameter, and the diameter of the particles.