Domain decomposition method with nonmatching grids for acoustic scattering problems

Efficient iterative methods for the numerical solution of three-dimensional acoustic scattering problems are considered. The original exterior boundary value problem is approximated by truncating the unbounded domain and by imposing a nonreflecting boundary condition on the artificial boundary. The...

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Main Author: Heikkola, Erkki
Format: Doctoral dissertation
Published: 1997
Online Access: https://jyx.jyu.fi/handle/123456789/100562
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author Heikkola, Erkki
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description Efficient iterative methods for the numerical solution of three-dimensional acoustic scattering problems are considered. The original exterior boundary value problem is approximated by truncating the unbounded domain and by imposing a nonreflecting boundary condition on the artificial boundary. The finite element discretization of the approximate boundary value problem is performed using locally fitted meshes, and the mesh equations are solved with algebraic fictitious domain methods with separable preconditioners. The iterative solution method is realized in a low-dimensional subspace, and partial solution technique is applied to the linear systems with the preconditioner. A domain decomposition method with nonmatching discretization grids is introduced for the solution of elliptic equations in exterior domains. This method uses a macro-hybrid formulation based on domain decomposition to couple spherical and cartesian coordinate systems. Finite element discretization of the hybrid formulation leads to a linear system in the saddle-point form. For this system, a special preconditioner based on fictitious domains is introduced such that the subspace of constraints becomes invariant with respect to the corresponding preconditioned iterative procedure. Several numerical experiments demonstrate the applicability and efficiency of the approach. A new direct method is proposed and analyzed for solving approximately general partial solution problems for linear systems with separable matrices arising from the finite difference discretization of constant-coefficient elliptic equations. The method requires the discretization grid to be only quasiuniform and is thereby applicable to a much wider range of problems than the earlier approximate partial solution methods, which are typically restricted to uniform grids. The asymptotic computational cost of the new method is shown to be lower than the cost of the classical partial solution algorithm. The implementation of the algorithm is considered and results of numerical experiments are reported.
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For this system, a special preconditioner based on fictitious domains is introduced such that the subspace of constraints becomes invariant with respect to the corresponding preconditioned iterative procedure. Several numerical experiments demonstrate the applicability and efficiency of the approach. A new direct method is proposed and analyzed for solving approximately general partial solution problems for linear systems with separable matrices arising from the finite difference discretization of constant-coefficient elliptic equations. The method requires the discretization grid to be only quasiuniform and is thereby applicable to a much wider range of problems than the earlier approximate partial solution methods, which are typically restricted to uniform grids. The asymptotic computational cost of the new method is shown to be lower than the cost of the classical partial solution algorithm. 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spellingShingle Heikkola, Erkki Domain decomposition method with nonmatching grids for acoustic scattering problems
title Domain decomposition method with nonmatching grids for acoustic scattering problems
title_full Domain decomposition method with nonmatching grids for acoustic scattering problems
title_fullStr Domain decomposition method with nonmatching grids for acoustic scattering problems Domain decomposition method with nonmatching grids for acoustic scattering problems
title_full_unstemmed Domain decomposition method with nonmatching grids for acoustic scattering problems Domain decomposition method with nonmatching grids for acoustic scattering problems
title_short Domain decomposition method with nonmatching grids for acoustic scattering problems
title_sort domain decomposition method with nonmatching grids for acoustic scattering problems
title_txtP Domain decomposition method with nonmatching grids for acoustic scattering problems
url https://jyx.jyu.fi/handle/123456789/100562 http://www.urn.fi/URN:ISBN:978-952-86-0575-1
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