An efficient exponential time integration method for the numerical solution of the shallow water equations on the sphere

JOURNAL OF COMPUTATIONAL PHYSICS

卷:322

Article

Gaudreault, Stephane¹  Pudykiewicz, Janusz A.¹ 

[1] Environm Canada, Sci & Technol Branch, Rech Previs Numer Atmospher, 2121 Route Transcanadienne, Dorval, PQ H9P 1J3, Canada

关键词: Shallow water equations;    Exponential time integration methods;    Numerical Weather Prediction;    Time integration;    Exponential methods;   

DOI  :  10.1016/j.jcp.2016.07.012

来源: Elsevier

【 摘 要 】

The exponential propagation methods were applied in the past for accurate integration of the shallow water equations on the sphere. Despite obvious advantages related to the exact solution of the linear part of the system, their use for the solution of practical problems in geophysics has been limited because efficiency of the traditional algorithm for evaluating the exponential of Jacobian matrix is inadequate. In order to circumvent this limitation, we modify the existing scheme by using the Incomplete Orthogonalization Method instead of the Arnoldi iteration. We also propose a simple strategy to determine the initial size of the Krylov space using information from previous time instants. This strategy is ideally suited for the integration of fluid equations where the structure of the system Jacobian does not change rapidly between the subsequent time steps. A series of standard numerical tests performed with the shallow water model on a geodesic icosahedral grid shows that the new scheme achieves efficiency comparable to the semiimplicit methods. This fact, combined with the accuracy and the mass conservation of the exponential propagation scheme, makes the presented method a good candidate for solving many practical problems, including numerical weather prediction. Crown Copyright (C) 2016 Published by Elsevier Inc.

【 授权许可】

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