丘陵地形を過ぎる安定成層流の2次元数値シミュレーション

格子分解能と数値計算法の影響について

抄録

A two-dimensional numerical simulation of stably-stratified flows past a cosine-shaped hill is made by using a finite-difference method (FDM) with a third-order upwind-difference scheme at Re=2000. In order to simulate the flow around the hill with high accuracy, a boundary-fitted coordinate (BFC) grid is used. First, effects of the grid resolution in the streamwise direction on numerical results are discussed, and it is shown that for the calculation with the stably-stratified flow the grid resolution is more important than that with the non-stratified flow. Next, effects of the numerical method on the convergence of the successive over relaxation (SOR) method in solving the pressure Poisson equation are examined, because the iteration solution of the pressure Poisson equation is the most time-consuming part in the overall solution procedure. The numerical method based on a collocated grid shows much more efficiency for the CPU time than that with a regular grid.