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A Four-Equation Eddy-Viscosity Approach for modeling Bypass Transition

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Advances in Applied Mathematics and Mechanics 2014年第4期6卷 523-538页

作者： Guoliang Xu Song Fu China Aerodynamics Research and Development Center Mianyang 621000China School of Aerospace Tsinghua UniversityBeijing 100084China

It is very important to predict the bypass transition in the simulation of flows through *** paper presents a four-equation eddy-viscosity turbulence transition model for prediction of bypass *** is based on the SST turbulence model and the laminar kinetic energy concept.A transport equation for the non-turbulent viscosity is proposed to predict the development of the laminar kinetic energy in the pre-transitional boundary layer flow which has been observed in *** turbulence breakdown process is then captured with an intermittency transport equation in the transitional *** performance of this new transition model is validated through the experimental cases of T3AM,T3A and *** in this paper show that the new transition model can reach good agreement in predicting bypass transition,and is compatible with modern CFD software by using local variables.

关键词： Bypass transition non-turbulent viscosity free stream turbulence turbulence model

Numerical Simulation of Gas-Solid Flow in Square Cyclone Separators with Downward Exit

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Journal of Harbin Institute of Technology(New Series) 2014年第2期21卷 83-90页

作者： Noé-Landry-Privace M'Bouana Fei-Xiang Zhao Qing-Hong Zhang Hui-Lin Lu School of Energy Science and Engineering Harbin Institute of Technology

Cyclone separators are widely used in industrial applications. The separation efficiency and pressure drop are the most important parameters to evaluate the performance of processing system. In the simulations,the flow behavior of gas and particles within a square cyclone separator is simulated by means of computational fluid dynamics. The RNG k- ε model and the Reynolds stress model( RSM) are used to model gas turbulence. The flow behavior is examined in the term of tangential velocity components,static pressure and pressure drop contour plots for flow field and solid volume fraction. The effects of the turbulence model and solid volume fraction on the square cyclone are discussed. The results indicate that the pressure drop increases with the increase of solid volume fraction,and increase with the increase of inlet velocities for two turbulence models, moreover,the simulations results are compared with pressure field. For all runs,the RSM model gives a higher pressure drop compared to the RNG k- ε model. The RSM model provides well the forced vortex and free vortex,and captures better the phenomena occurring during intense vortex flow in the presence of walls within cyclone separators.

关键词： CFD square cyclone turbulence model two-phase flow solid volume fraction.

STUDIES　OF　SOLID－LIQUID　TWO－PHASE　TURBULENT　FLOWS　AND　WEAR　IN　HYDRAULIC　TURBOMACHINERY

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Journal of Hydrodynamics 1996年第2期8卷 72-76页

作者： Liu, Xiaobing Sichuan Inst of Technology Chengdu China

The Lagrangian equation of motion for solid particles in an arbitrary flow field is derived. The linear differential equation form and the general solution of this equation are obtained. Motion of solid particles in dilute solid-liquid turbulent flows is numerically solved and analysed. The K-εtwo-equation turbulence model, the volume fraction turbulence model, the mixed Eulerian-Lagrangian turbulence model, and the dense mixture turbulence model as well as the erosive wear model are developed. Using these models, the turbulent flows and the erosive wear in some hydraulic turbomachinery ducts are numerically predicted. The numerical results show good agreement with the experiments.

关键词： hydraulic turbomachinery solid-liquid two-phase flows turbulence model erosive wear numerical prediction

NUMERICAL SIMULATION OF THE FLOW FIELD IN A THERMAL PLASMA REACTOR

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Applied Mathematics and Mechanics(English Edition) 1990年第12期11卷 1167-1170页

作者：李国彦 1. Kunming Institute of Technology Kunming

A numerical simulation is presented for a thermal plasma reactor with particle-trajectory model in this paper. Turbulance is considered by using simple SGS model. The governing equations are solved by means of the algorithm of SIMPLER. The calculated results give the velocity and the temperature fields within plasma reactor, and the trajectories of the injected particles.

关键词： plasma flow field numerical simulation turbulence model

Experimental and numerical investigation of gas diffusion under an urban underground construction

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能源与人工环境(英文) 2021年第4期2卷 436-444页

作者： Kang Zhou Fei Li Hao Cai Yibin Yang Fusheng Peng Li Chen Junyi Zhuang Department of HVAC College of Urban ConstructionNanjing Tech UniversityNanjing 210009P R China Engineering Research Center of Safety and Protection of Explosion&Impact of Ministry of Education Southeast UniversityNanjing 211189P R China College of National Defense Engineering Army Engineering UniversityNanjing 210007P R China PLA Unit 96784 LuoyangHenan 471399P R China

Rapid increase of urban underground constructions has a great consideration of underground environment safety and how to expel toxic gasses out of tunnels *** utility tunnel is a typical urban tunnel construction with multiple underground pipelines including gas pipelines,and it is necessary to investigate characteristic of gas diffusion and monitor gas leakage to ensure tunnel *** this study,the experimental measurements of airflow and gas distributions were conducted in a 10 m full-scaled utility tunnel mockup,and gas diffusion characteristic was also *** simulation of utility tunnel leakage was also conducted by computational fluid dynamics(CFD).Different turbulence models and different air supply diffuser models were compared via the experimental results based on visualization and the relative root-mean-square error(RRMSE)index,which quan-titated the difference between the numerical and experimental *** results showed that the standard k−εturbulence model and random air opening model could provide better results than other *** to the experimental data analysis,it was necessary to consider the optimization of monitoring detector arrangements in actual utility *** study provided basic experimental data and the validated numerical model for the leakage source identification and underground tunnels simulation research.

关键词： Urban tunnel Gas leakage Gas dispersion CFD turbulence model Air supply diffuser

Mathematical model of Fluid Flow and Solidification in Mold Region of Continuous Slab Casting

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Tsinghua Science and Technology 2003年第1期8卷 83-89页

作者：谭利坚沈厚发柳百成 Department of Mechanical Engineering Tsinghua University

To simulate the phenomena in the mold region of continuous casting by coupling fluid flow and solidification, a three-dimensional mathematical model has been developed based on the K-ε turbulence equations and the SIMPLER algorithm. A pseudo source term was introduced into the energy equation to account for the latent heat and kinetic energy. The fluid flow in the mushy zone was calculated by defining the fluid viscosity as a function of the solid fraction in the mushy zone. Fine meshes in the solid region improve convergence and reduce iteration time. Comparison of the fluid flow and temperature distribution with and without solidification shows that although the solid shell in the mold is thin, it still greatly affects the flow pattern. The numerical results obtained provide details of the fluid flow and solidification phenomena which can be used to optimize the nozzle structure and other process parameters in continuous casting.

关键词： fluid flow solidification mushy zone turbulence model numerical simulation continuous casting

New turbulence modeling for air/water stratified flow

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Journal of Ocean Engineering and Science 2020年第1期5卷 55-67页

作者： M.Ghafari M.B.Ghofrani Department of Energy Engineering Sharif University of TechnologyAzadi Ave.TehranIran

The prediction of interfacial turbulence characteristics is one of the still challenging of two-phase stratified *** evaluation of some important parameters such as interfacial heat transfer coefficient based on turbulence kinetic energy and turbulence dissipation rate in some models,intensifies the importance of turbulence flow correct *** gradient of velocity and turbulence kinetic energy at the interface of two-phase stratified flow leads to a major overestimation or underestimation of flow characteristics without any special *** of a source function of turbulence eddy frequency at the interface is one of the common solution employed in past *** this solution remedies some shortcomings of traditional methods in smooth stratified flow,its application in wavy stratified flow needs the other *** examination of turbulence characteristics near the free surface reveals that,in addition to turbulence eddy frequency,the other source function of turbulence kinetic energy should be considered near the free ***,a new source function of turbulence kinetic energy is proposed at the interface based on flow *** new method has been employed for Fabre et al.(1987)experiment designed for air/water stratified *** results of simulation have a good agreement with experimental data and turbulence characteristic can be captured near the free surface.

关键词： Stratified flow turbulence model turbulence kinetic energy Source function

Effects of ripple cross angles and turbulence models on wet curtain resistance

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International Journal of Agricultural and Biological Engineering 2019年第4期12卷 43-46页

作者： Tao Ding Lumeng Fang Zhengxiang Shi Baoming Li Yang Zhao College of Water Resources and Civil Engineering China Agricultural UniversityBeijing 100083China Beijing Engineering Research Center for Safety and Energy-Saving Technology for Water Supply Network Systems Beijing 100083China Key Laboratory of Agricultural Engineering in Structure and Environment Beijing 100083China

To study the influence of ripple cross angles on the resistance of wet curtains,wet curtains with different ripple cross angles(45°/45°,45°/15°)were tested on agricultural ventilation equipment performance testing benches,and the static pressure drop under different wind speeds(1-3 m/s)was *** turbulence models(κ-ε,RNGκ-ε,κ-ω,SSTκ-ω)were adopted for numerical simulations of the two types of wet curtain,and the simulations’results were compared with those of *** average errors found are 41.1%,48.7%,27.1%,and 27.8%,respectively,and theκ-ωmodel is found to be the most suitable one for the calculation of wet curtain resistance among the four turbulence *** using theκ-ωturbulence model,the static pressure drop performances of wet curtains with ripple cross angles 45°/35°and 45°/25°were *** increases with wind speed and ripple cross angles,and a large ripple cross angle has a higher resistance growth rate with increasing wind speed.

关键词： wet curtain ripple cross angle resistance turbulence model ventilation cooling and humidifying system

Numerical Investigation of Developing Turbulent Flow in a Helical Square Ductwith Large Curvature

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Journal of Thermal Science 2001年第1期10卷 1-6页

作者： Gao Hui,Guo Liejin (State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China ) State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

A fully elliptic numerical study has been carried out to investigate the three-dimensional turbulent developing flow in a helical square duct with large curvature. A two-layer zonal model is proposed and used, in which the whole region is divided into a viscosity-affected near wall layer and a fully turbulent region. A DSM closure is applied in the former, and a one-equation model is solved in the latter. The results presented in this paper cover a Reynolds number range of (l- 10) x 104. The development of flow is found to be dominated by radial pressure gradient and Dean-type secondary motion. The distribution of Reynolds stresses in fully developed flow exhibit a complex pattern of turbulence anisotropy The development of peripherally averaged friction factor and the distribution of local friction factor in fully developed flow are given and discussed.

关键词： curved pipe developing flow turbulence model numerical simulation.