Simple simulation model of the generation of clouds by the flow over an isolated mountain
摘要
A simple model to simulate the formation of clouds by the wind blowing over a mountain is proposed in this study. The flow is assumed to be stably stratified. The incompressible Navier-Stokes equations together with the advection equation of density are chosen for the basic equations. These equations are solved numerically by the standard MAC method. Third order upwind difference is employed for the approximation of the nonlinear terms of the Navier-Stokes equation. Finite number of particles is used to express the clouds. At first, each particle has its own temperature and humidity and is moved according to the velocity of the flow field. When the humidity becomes 100%, the particle is assumed to become a small cloud and is displayed. The effects of the humidity as well as the wind speed etc. on the formation of the clouds are investigated and we can obtain reasonable results which are consistent with our everyday experience.