Application of some iterative methods to wind field calculation

Abstract

This paper describes the reduction of computation time of a large sparse linear equations obtained by discretization of a three-dimensional Poisson's equation using the finite difference method. The equation is induced from wind field calculations, which are needed for evaluation of environmental consequences due to radioactive effluents. Various iterative methods, such aS ICCG, MICCG, ILUCR and MILUCR methods, are applied to solving linear equations and are compared with SOR method. The optimum value of the acceleration factor of SOR method can be obtained numerically according to atmospheric stability for each nuclear site, and the iterations are minimized by using this optimum value. The computation time for MICCG or MILUCR method is a half of that for SOR method. The ILUCR method is better than SOR method, because it does not use acceleration factor and the computation time is shorter. The use of vector computer drastically reduces the computation time, and all the iterative methods are applicable. A scalar computer, however, favors the use of MILUCR or MICCG methods because of a half of the computation time for SOR method. © 1987, Atomic Energy Society of Japan. All rights reserved.