非定常不可压绕流的有限元-有限差分计算

FDM-FEM Approach for Unsteady Incompressible Flow Computations

本文用一种有限元-有限差分混合法解不可压非定常Navier-Stokes方程来模拟非定常绕流。在同一时间步的不同计算步中,用三阶迎风差分格式离散动量方程中的对流项,压力修正方程用有限元离散,离散后的方程用直接法求解。本文给出了雷诺数(Re)为1200时的圆柱绕流结果。模拟了突然起动过程中对称主涡和二次涡的发展过程,以及柱后涡街的发展过程中主涡和二次涡的形成、合并、脱落过程。

Unsteady incompressible flow around a circular cylinder is analysed by direct integration of Navier-Stokes equations using a hybrid method between a finite-difference method (FDM) and a finite-element method (FEM). In this method, a high-order upwind scheme expressed easily in FDM is used to discrete convective terms in the N-S equations. The Poisson equation for the correct pressure P is solved by FEM. The Reynold number is 1200. Some meaningful results are gotten.