完全耦合层边界条件在圆柱绕流DNS中的应用

PERFECTLY MATCHED LAYER BOUNDARY CONDITIONS USING IN DNS OF FLOW AROUND CYLINDER

数值模拟圆柱绕流问题是计算流体力学和计算气动声学中的一个经典问题,要准确模拟这一类问题,远场无反射边界条件是一个关键环节。本文采用适用于主控方程为Navier-Stokes方程的完全耦合层无反射边界条件对低雷诺数条件下圆柱绕流进行直接数值模拟,研究了计算域大小的选取对数值结果的影响。数值模拟研究表明:(1)由完全耦合层边界条件产生的相对反射误差很小;(2)如果仅是为了获得圆柱附近的流场和声场信息,采用完全耦合层边界条件可以选用较小的计算域;(3)适当增加计算域的上下边界宽度,可以很大程度地减小右边界的宽度,从而在保证精度的情况下减小计算量。

Numerical simulation of flow around cylinder is a classical problem in computational fluid dynamics and computational aeroacoustics.The non-reflection boundary condition is one of the key technologies during the simulation.Perfectly Matched Layer（PML） boundary conditions for Navier-Stokes equations are used in the direct numerical simulation of flow around cylinder at low Reynolds number.And the effect of the size of computational domains on solutions is numerically studied.Numerical results reveal that：（1） Relative reflection errors caused by PML boundary conditions are very small.（2） Smaller computational domains can be used for the flow and acoustic field around the cylinder if PML boundary conditions are applied.（3） Slightly increasing of the width of up and down boundaries of the computational domain can greatly reduce the width of the outflow boundary,and maintain high accuracy of solutions with less calculation time.