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Validation of a RANS transition model using a high-order weighted compact nonlinear scheme

Science China(Physics,Mechanics & Astronomy) 2013年第4期56卷 805-811页

作者： TU GuoHua DENG XiaoGang MAO MeiLiang State Key Laboratory of Aerodynamics China Aerodynamics Research & Development Center Science and Technology on Scramjet Laboratory Hypervelocity Aerodynamics Institute of CARDC National University of Defense Technology Computational Aerodynamics Institute China Aerodynamics Research & Development Center

A modified transition model is given based on the shear stress transport (SST) turbulence model and an intermittency transport equation. The energy gradient term in the original model is replaced by flow strain rate to saving computational costs. The model employs local variables only, and then it can be conveniently implemented in modern computational fluid dynamics codes. The fifth-order weighted compact nonlinear scheme and the fourth-order staggered scheme are applied to discrete the governing equations for the purpose of minimizing discretization errors, so as to mitigate the confusion between numerical errors and transition model errors. The high-order package is compared with a second-order TVD method on simulating the transitional flow of a flat plate. Numerical results indicate that the high-order package give better grid convergence property than that of the second-order method. Validation of the transition model is performed for transitional flows ranging from low speed to hypersonic speed.

关键词： hypersonic boundary layer transition transition model intermittency factor high-order schemes

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Artificial neural network-based one-equation model for simulation of laminar-turbulent transitional flow

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Theoretical & Applied Mechanics Letters 2023年第1期13卷 50-57页

作者： Lei Wu Bing Cui Zuoli Xiao State Key Laboratory for Turbulence and Complex Systems College of EngineeringPeking UniversityBeijing 100871China Inspur Electronic Information Industry Co. LtdBeijing 100085China HEDPS and Center for Applied Physics and Technology College of EngineeringPeking UniversityBeijing 100871China Nanchang Innovation Institute Peking UniversityNanchang 330008China

A mapping function between the Reynolds-averaged Navier-Stokes mean flow variables and transition intermittency factor is constructed by fully connected artificial neural network(ANN),which replaces the governing equation of the intermittency factor in transition-predictive Spalart-Allmaras(SA)-γ*** taking SA-γmodel as the benchmark,the present ANN model is trained at two airfoils with various angles of attack,Mach numbers and Reynolds numbers,and tested with unseen airfoils in different flow *** a posteriori tests manifest that the mean pressure coefficient,skin friction coefficient,size of laminar separation bubble,mean streamwise velocity,Reynolds shear stress and lift/drag/moment coefficient from the present two-way coupling ANN model almost coincide with those from the benchmark SA-γ***,the ANN model proves to exhibit a higher calculation efficiency and better convergence quality than traditional SA-γmodel.

关键词： Transition Turbulence Eddy-viscosity model Artificial neural network intermittency factor

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Basic Study on Perfect Push-Pull Local Ventilation

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Journal of Energy and Power Engineering 2012年第12期6卷 1940-1944页

作者： Yukihiro Hattori Koichi Nakabayashi Osami Kitoh Motoyuki Ito Aichi University of Technology Automotive Junior College Gamagori Aichi pref 443-0047 Japan Aichi University of Technology Gamagori city Aichi pref 443-0047 Japan Nagoya Institute of Technology Nagoya city Aichi pref 466-8555 Japan

In this study, the authors experimentally investigated the changes of the mean velocity component profiles, half-widths （b12）, turbulence intensities, Reynolds shear stress and intermittency of turbulence of a transient plane turbulent jet developing from a jet exit into a hood opening. The values of maximum mean-velocity and half-widths of the axial velocity profile along the center-line of the jet are greater than those for a fully developed two-dimensional jet. Turbulence intensity in the axial direction is not affected by the flow rate ratio. At the same time, turbulence intensity in the lateral direction becomes greater as the hood is approached and the flow rate ratio Q3/Q1 becomes larger （QI is jet flow rate from nozzle and Q3 is suction flow rate produced by the hood）. These experimental results are in accord with the distributions of production terms in the axial and lateral directions. Reynolds shear stress becomes smaller as the flow rate ratio becomes larger near the hood. Dimensionless distance y1/br2, from the center axis of the flow to the point where intermittency factor y becomes a constant value, narrows as the flow rate ratio becomes larger near the hood.

关键词： Turbulence intensity intermittency factor Reynolds shear stress push-pull ventilation.

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