이차원 정상, 비정상 유동장에서의 랜덤와류법의 수치적 검증

Abstract

Random Vortex Method, simulating the vortex dominant viscous flowhields via discrete vortex particles is improved in the accuracy by rectifying numerical algorithm and selecting the numerical parameters carefully. Test of the improved method is accomplished through applying to laminar boundary layer by using the incompressible, two-dimensional Navier-Stokes equations, and to the viscous diffusion problem. Verification of the modified method on unsteady flow is made by applying to the diffusion equation and the problem of an impulsively starting circular cylinder. For the problem of an impulsively starting circular cylinder, vortex structure including α,β phenomena are clearly captured for Reynolds numbers of 550, 3000 and 9500, respectively. Excellent agreement with experiments are achieved of flow patterns and velocity for the wide range of Reynolds numbers. Critical improvements in the method is in the algorithms for higher order time integration, the selection of vortex particle size, and the treatment of vortex particle near the wall.