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Journal of Iron and Steel Research(International) 2003年第2期10卷 5-9页

作者： ZHANG Jian University of Science and Technology Beijing

A steady three-dimensional fluid flow and solidification model was built based on CFD software by high-Reynolds-number and Lam-Bremhorst low-Reynolds-number k-ε model. During the simulation, the fixed-grid enthalpy-porosity technique was used to represent the solidification, and Darcy law was adopted to simulate the flow in mushy region. The prediction for steel flow and solidification was evaluated by the comparison of two turbulence models. It is found that both Lam-Bremhorst low-Reynolds-number and high-Reynolds-number k-ε models predict the same trend of the steel flow and temperature distribution. However, due to the effect of turbulent flow on heat transfer, the low-Reynolds-number turbulence model predicts longer penetration depth of molten steel in sub-mold region, less shell growth and higher shell surface temperature at the narrow face compared with standard k-ε model.

关键词： continuous slab caster solidification steel flow turbulence model numerical simulation

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 turbomachinery.This paper presents a four-equation eddy-viscosity turbulence transition model for prediction of bypass transition.It 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 experiments.The turbulence breakdown process is then captured with an intermittency transport equation in the transitional region.The performance of this new transition model is validated through the experimental cases of T3AM,T3A and T3B.Results 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

Comparison of different turbulence models in predicting cohesive fluid mud gravity current propagation

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International Journal of Sediment Research 2020年第5期35卷 504-515页

作者： Seyed-Mohammad-Kazem Emami Sayed-Farhad Mousavi Khosrow Hosseini Hesam Fouladfar Majid Mohammadian Faculty of Civil Engineering University of Semnan Iran Water & Power Resources Development Company 3. Department of Civil Engineering University of Ottawa

A numerical study of propagation of cohesive fluid mud gravity currents in the form of lock-exchange was done using the OpenFOAM open source toolbox.An Eulerian approach solution for three separate phases was developed by incorporating a rheological model to predict the front position of cohesive fluid mud gravity currents.The model also simulates features in the complete movement phases including slumping,self-similar,and viscous in which the dynamics of propagation are affected by the balance of viscous and buoyancy forces,and the inertia force is negligible.The influence of using different turbulence models containing sub-grid scale(SGS),modified SGS,detached eddy simulation(DES),delayeddetached eddy simulation(DDES),Launder-R eece-Rodi(LRR),and k-ε models on the accuracy of simulation results was evaluated by comparing with available experimental data.The results show that the selection of the proper turbulence model is one of the most important issues for this type of the numerical modeling.The more efficient turbulence model was suggested and tabulated for each stage of propagation and different selected concentrations of 1,045,1,140,and 1,214 g/L.Although different turbulence models(except k-ε) lead to front propagation dynamic simulation results that are in good agreement with the experimental measurements in the early stage of propagation for low concentrations,only DES,SGS,and modified SGS are able to capture the Kelvin-Helmholtz instability vortex shapes at the dense fluid interface,which is the main characteristic of the gravity current through the slumping phase.The calculated accuracies of SGS and modified SGS in predicting gravity current propagation for the both self-similar and viscous phases also are slightly better than DES,DDES,and LRR model results.The results of this study confirmed the performance and efficiency of the modified SGS model in which the interaction coefficients between phases are calibrated for the numerical modeling of fluid mud gravity current propagation.

关键词： Gravity current turbulence model Numerical simulation Cohesive particles Rheology

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 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

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

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

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)

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 effectively.The 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 safety.In 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 investigated.Numerical 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.The results showed that the standard k−εturbulence model and random air opening model could provide better results than other models.According to the experimental data analysis,it was necessary to consider the optimization of monitoring detector arrangements in actual utility tunnels.This 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

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 determined.Four 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 experiments.The 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 models.By using theκ-ωturbulence model,the static pressure drop performances of wet curtains with ripple cross angles 45°/35°and 45°/25°were calculated.Resistance 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

modelLING OF THE PRESSURE-VELOCITY CORRELATION IN turbulence DIFFUSION

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Acta Mechanica Sinica 1992年第3期8卷 208-214页

作者：符松 Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China

Most current computations of trubulent flows with second-moment closure adopt the diffusion mo- dels which neglect the effect of pressure-velocity correlation.ln the present paper the importance of this correlation effect is elucidated the neglect of this effect accounts for some major defects in the wide application of the se- cond-moment closures.Through the relation between and ,established by Lumley,we propose here a new turbulence diffusion model which takes into consideration the pressure effect.Applications of this new model in the computation of shearless turbulence mixing layer and plane-and round-jet flows show that the spreading rate of these flows can be satisfactorily captured.

关键词： turbulence model pressure-velocity corelation Reynolds stress jet

Fluctuation Velocity Correlation Closure model for Dense Gas-Particle Turbulent Flow

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Journal of Shanghai Jiaotong university(Science) 2012年第4期17卷 447-451页

作者：曾卓雄陈超杰 Aeronautic and Mechanical Engineering college Nanchang Hangkong University

turbulence model of kg-εg-kp-εp-kpg-θ is proposed.In the model,the two-phase velocity correlation turbulent kinetic energy k pg is modeled by transport equation.To close this turbulence model,algebraic expressions of two-phase Reynolds stresses and two-phase velocity correlation variable are established by considering both gas-particle interaction and anisotropy.This turbulence model is used to simulate dense gas-particle flow in a riser and in a downer.The predicted results show the core-annulus flow structure observed in the riser and the skin effect of particle concentration in the downer.The present model gives simulation results in much better agreement with the experimental results than those obtained by kg-εg-kp-εp-θmodel which is simply closed using a semi-empirical dimensional analysis.

关键词： gas-particle flows turbulence model numerical simulation