嵌套网格的海洋过程模型

NESTED GRID MODELS FOR OCEAN PROCESSES

在有多个区域的算例中,我们介绍了两种处理方法以允许计算信息在边界处能够自由传递。第一种方法是基于给定的一个交界面以实现最少的边界反射波,它在各个次区域之间只单纯计算初值问题。第二种方法则是在各个次区域之间利用压力边界条件,同时利用后退边界方法来减少压力误差。开始时,计算区域叠加在一起,但是利用后退边界在几个时间步长之后可以消除计算区域的叠加,从而可以避免近似边界条件的应用。这种方法有效防止了计算误差在各个次区域边界处的累积,而且通过不断的舍去边界值减少了计算误差往其他区域的传播。最后介绍了这种方法在计算表面波、重力流以及表面波和内波相互结合的传播过程。

We present two schemes that allow information to travel freely through the computational boundaries of the multiple computational domains. The first method is based on an explicit interface that minimizes boundary reflections, as it solves purely initial - value problems at the interface between sub- domains. the second method assumes the pressure boundary conditions between sub- domains, but uses a receding boundary approach to minimize the pressure, errors. Initially, the domains overlap, but within a few time steps the overlap is eliminated by the receding boundaries, so repeated use of approximate boundary conditions is avoided. This prevents the accumulation of errors on the sub - domain boundaries and, furthermore, decreases the transfer of errors to the rest of the domain by continuously disearding boundary data. Successful applications of the method are presented for surface wave propagation, gravity currents and a combination of both surface and internal waves.