An Iterative Solver with a Convergence-Acceleration Technique for Pressure Field in an Uneven-Spacing Grid System

Abstract

A straightforward iterative method is developed for solving the pressure field in three-dimensional, anelastic, nonhydrostatic, mesoscale models with uneven-spacing grid systems for which direct FFT (fan Fourier transform) schemes cannot be applied. This method utilizes the ADI (alternating direct implicit) integration scheme and a convergence-acceleration technique (Orthmin) to reach the asymptotic solution for a Poisson equation. It also permits the use of various types of boundary conditions in three dimensions. The efficiency of this method in terms of computing time and accuracy is presented.