网格拓扑对圆柱绕流计算的影响研究

Study on the influence of grid topology on the calculation of flow around a cylinder

使用DDES湍流模型对流动复杂的亚临界雷诺数(Re=3900)圆柱绕流进行数值计算,重点从模型尺度调控、湍流结构捕捉能力及流场统计积分量等方面分析了不同网格拓扑对大分离流动求解精度的影响规律。计算结果表明:使用H型、C型网格拓扑及在远场设置非结构网格时,流场表现出良好的湍流谱生成能力,捕捉到较多的高频-小尺度涡结构,同时计算的阻力系数、回流区长度等物理量与实验值拟合较好;O型网格拓扑流场耗散较大,计算精度相对较低。计算效率与网格数量呈线性关系,但计算精度与网格数量不一定正相关,工程计算中应合理选择兼顾计算精度及效率的网格划分方式。

The flow past in a circular cylinder at sub-critical Reynolds number is simulated using the delayed detached-eddy simulation model.The impact of grid topologies in massively separated flows are further analyzed through the simulated scale distribution,the reproducing effect of turbulence structure and the summary of statistical data.From the assessment,it shows good turbulence spectrum generation capability when using H topology,C topology and unstructured grids at far field,reproducing reasonable small-scale turbulence eddy,drag coefficient and so on.While it turns out that the simulation using O topology in separated wake region appears more dissipative,which means lower accuracy.The compared data presents a linear relationship between computing efficiency and grids number,while it may be not same between simulation accuracy and grids number.It is recommended that suitable grid generation approach balancing accuracy and efficiency should be considerable in engineering calculation.