中等雷诺数圆球绕流的数值研究

Numerical study of uniform flow over sphere at intermediate Reynolds numbers

采用三维黏性不可压缩流场分块耦合计算方法计算圆球绕流问题.动量方程分别采用高精度和常规精度离散,压力泊松方程采用二阶中心差分格式离散.出口边界条件为无反射边界条件;计算网格为全流场封闭的H-O型网格.计算了雷诺数为8.9～1000.0时圆球绕流受到的阻力,分析尾涡形状及长度随雷诺数的变化规律.计算得到的阻力系数和尾涡长度与实验结果符合较好.用高精度算法研究了尾涡结构问题,在雷诺数为1000.0时成功地获得了尾流发夹涡现象.

Numerical simulation of uniform flow past a sphere was done using 3D DDM (domain decomposition method). The momentum equation was discretized using generic low order scheme and high order compact scheme respectively, and the pressure Poisson equation using second-order central scheme. A believable reflectless condition was applied in the outer boundary. An H-O type of grid was constructed in the domain. The drag on the sphere was calculated for Reynolds numbers 8.9 to 1000.0, and the shape and length of the wake behind the sphere were investigated. The results agreed well with the experimental results. The wake structure was also investigated using high-order accuracy methods, which showed that the flow was steady axisymmetric for Re<200.0, and steady, non-axisymmetric for 200.0<Re<270.0. The present study successfully simulated the hairpin vortices in the wake for Re=1000.0.