On the Solution of Elliptic Problems on Overset/Yin–Yang Grids

Abstract

Abstract The heterogeneity and the singularity of the grid are major factors in the weak scalability of longitude–latitude grid–based atmospheric models on massively parallel machines. Overset grids and, in particular, the Yin–Yang grid, are potential solutions to this problem. Using semi-implicit time marching schemes requires the solution of an elliptic problem on the particular grid. For overset/composite grids to be a viable approach, the solution of the elliptic problem has to be at least as accurate and efficient as using a single grid. This paper proposes combining the overset/Yin–Yang composite elliptic problems in one system using Krylov-type solvers and shows that the solution on overset grids is highly efficient because of the improved grid’s homogeneity.