低雷诺数湍流模型的网格特征

Mesh feature of low Reynolds number turbulence model

低雷诺数模型目前主要应用于二维简单流动的数值仿真中,为研究该湍流模型在三维复杂流动计算中的网格特征,选取不同系列的车身面网格尺寸、车身壁面第一层边界层与壁面法向高度以及边界层层数等3组网格参数,利用ANSYS对阶背式MIRA模型外流场进行数值仿真.数值仿真结果与风洞试验的结果对比表明：数值计算得到的车身表面平均y＋值随面网格尺寸增加而呈现减小趋势;网格方案对气动力因数和车身表面压力因数分布影响显著,气动阻力因数仿真值与试验值误差的变化区间为0.83%-7.93%,气动升力因数误差变化区间为10%-104%;气动阻力因数和气动升力因数均随着边界层层数的增加而增大,边界层层数为5时可以得到兼顾气动力因数精度和车身表面压力因数精度的较优仿真结果.

The low Reynolds number model is mainly used to simulate simple 2D flows. To study mesh feature of the model applied in complex 3D flow,three groups of parameters,including different series of car body surface mesh size,the normal height of first boundary layer and wall boundary layers number,are selected to simulate the notchback MIRA flow by ANSYS. According to the comparison between numerical simulation results and wind tunnel test results,a conclusion is drawn that,the facet average y＋of car body in simulation decreases with the increase of surface mesh size; the mesh scheme affects the aerodynamic force factors and surface pressure factor distribution on body surface significantly with an aerodynamic drag factor error variation range of 0. 83% - 7. 93% and aerodynamic lift factor error change interval of 10% - 104%; with the increase of boundary layers number,the aerodynamic drag factor and the aerodynamic lift factor increases; when the wall boundary layer number is five,a better simulation result can be obtained,which can ensure the accuracy of both aerodynamic factors and body surface pressure factor.