嵌边法出流条件在可压缩流直接数值模拟中的应用

以嵌边法为出口边界条件试算了亚、超声速平板边界层扰动波的演化、超声速流中涡的传播、亚声速平板边界层尾缘扰动的演化等,以验证嵌边法作为出流条件在可压缩流中的有效性。然后,探讨了嵌边法有关参数的选取问题。

The application of fringe method as the outflow boundary condition for the direct numerical simulation of compressible flows

For numerical simulations of compressible flows,characteristic boundary conditions are usually used to ensure that the disturbances pass through the boundary without causing reflections.However,sometimes,they do not yield satisfactory results for unsteady flows.On the other hand,"fringe method",also called "buffer zone method",has been proved to be effective in guarantee non-reflection for incompressible flows.Its main idea is that a fringe,or buffer zone, is added to the original computational domain,in which the governing equations are modified,such that disturbances are almost totally damped in propagating through this buffer zone,so there will be no disturbance to be reflected at the exit of the buffer zone.In this paper,by applying the "fringe method" to several unsteady compressible flows,such as the evolution of disturbances in subsonic and supersonic boundary layers,vortex convection in a supersonic flow,and the scattering of T-S waves at the trailing edge of a subsonic boundary layers on a flat plate,we showed that the fringe method is also effective in compressible flows.We proposed the criteria for the effectiveness of the method,and also discussed the effects of the parameters in the fringe method.