Numerical Solution of Karman Vortex Street behind a Circular Cylinder

[摘要] Two-dimensional non-steady viscous flow around a circular cylinder is investigated by solving the exact two-dimensional Navier-Stokes equations numerically for Reynolds numbers (Re) of 40 and 100. When Re is 40, a steady state solution can exist. On the other hand, when Re is 100, flow pattern does not become steady and the Karman vortex street appears.In the computations performed, these features are successfully realized, and the evolution of flow pattern of Kármán vortex is obtained.The quantity ∨‘⋅∇∨’ is also calculated for the purpose of studying the mechanism of dissipation of the vortex in the downstream side of the obstacle. The flow patterns as well as the drag coefficients obtained are in good agreement with the experimental data in both cases. In solving the problem using a finite domain, physical and computational boundary conditions should be posed properly. The method used was proved to be fairly satisfactory, if the domain is wide enough to contain the wake occuring behind the cylinder.

[学科分类] 大气科学