Volume 14, Issue 4
On Direct and Semi-direct Inverse of Stokes, Helmholtz and Laplacian Operators in View of Time-stepper-based Newton and Arnoldi Solvers in Incompressible CFD

H. Vitoshkin and A. Yu. Gelfgat


Commun. Comput. Phys., 14 (2013), pp. 1103-1119.

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  • Abstract

Factorizationof the incompressible Stokes operator linking pressureand velocity is revisited. The main purpose is to use the inverse of the Stokes operator with a large time step as a preconditioner for Newton and Arnoldi iterations applied to computation of steady three-dimensional flows and study of their stability. It is shown that the Stokes operator can be inversed within an acceptable computational effort. This inverse includes fast direct inverses of several Helmholtz operators and iterative inverse of the pressure matrix. It is shown, additionally, that fast direct solvers can be attractive for the inverse of the Helmholtz and Laplace operators on fine grids and at large Reynolds numbers, as well as for other problems where convergence of iterative methods slows down. Implementationof theStokes operatorinversetotime-steppingbased formulation of the Newton and Arnoldi iterations is discussed.

  • History

Published online: 2013-10

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