A Numerical Study of Two-Dimensional Airflow over an Isolated Mountain

[摘要] In order to simulate numerically one of the most remarkable phenomena of airflow over a mountain, i. e., the hydraulic jump on the lee side of the mountain, several numerical experimen tsare conducted with the shallow fluid flow system. Since the jump is a kind of shock phenomenon in the fluid, we need to use a highly accurate finite difference scheme. In the present study the one-step Lax-wendroff method is adopted.The following four cases of uniform flows are given as the initial conditions over the whole domain, i. e., two cases of subcritical flows and remaining two cases of supercritical flows. The results are in good agreement with those of the one-dimensional flow obtained by Houghton and Kasahara (1968). In the present experiment the jump is set up on the lee side of an isolated bell-shaped obstacle in one out of two subcritical flows and in one out of two supercritical flows. In another case of the subcritical flow the wave of wave length which is close to the width of the obstacle predominates. The flow pattern similar to that of the one-dimensional flow is observed in the remaining case of the supercritical flow. The zonal flow crossing over the obstacle is more predominant than that passing around the obstacle.

[学科分类] 大气科学