粘性涡方法在多圆柱绕流数值模拟中的应用

A NAVIER-STOKES SIMULATION OF FLOW A ROUND CIRCULAR CYLINDERS BY VISCOUS VORTEX METHOD

用粘性涡方法求解了涡量速度形式的二维不可压缩Navier—Stokes方程．利用分步方法分别求解无粘的对流运动和粘性扩散，粘性扩散用随机走步方法来处理，利用涡量交换技术来满足无滑移边界条件，同时为进一步减少计算量，在求解对流速度时，采用了多极子展开法加速技术使得计算量由N2的量级减少到NlogN的量级．数值模拟了单圆柱和双圆柱纵向排列的绕流流场．

The vorticity-velocity formulation of the Navier-Stokes equations are solved by viscousvortex method. The fractional step technique has been used. The viscous diffusion is treatedby a random walk method, the no-slip condition is not always enforced by the generationof new vortices at the boundary but instead by modifying the strength of the vortices inthe vicinity of the boundary; Particle-Box method is used to reduce the operation counts toO(Nlog N) from O(N2 ). The time dependent viscous flow around a circular cylinder andtwo circular cylinders in tandem arrangement of difference spacing at Reynolds numbers ofRe=3000 is presented.