MILU-CG方法和绕旋转圆柱流动的数值研究

本文采用以修正的不完全LU分解作预处理器的共轭梯度法(MILU-CG),结合高阶隐式差分格式,改进了作者(1992)提出的基于区域分解、有限差分法与涡法杂交的数值方法(HDV).系统地研究了雷诺数Re=1000,200,旋转速度比α∈(0.5,3.25)范围内,绕旋转圆柱从突然起动到充分发展,长时间内尾流旋涡结构和阻力、升力系数的变化规律.计算所得流线与实验流场显示相比,完全吻合.首次揭示了临界状态时的旋涡结构特性,并指出最佳升阻比就在该状态附近得到.

MILU-CG Method and the Numerical Study on the Flow around a Rotating Circular Cylinder

A hybrid finite difference method and vortex method(HDV),which is based on domain decomposition and proposed by the authors(1992),is improved by using a modified incomplete LU decomposition conjugate gradient method(MIL U-CG),and a high order implicit difference algorithm.The flow around a rotating circular cylinder at Reynolds number Re=1000,200 and the angular to rectilinear speed ratio A I(0.5,3.25)is studied numerically.The long-time full developed features about the variations of the vortex patterns in the wake,and drag,lift forces on the cylinder are given.The calculated streamline contours agreed well with the experimental visualized flow pictures. The existence of critical states and the vortex pat terns at the states are given for the first time.The maximum lift to drag force ratio can be obtained nearby the critical states.