A Method of Fundamental Solutions for Large-Scale 3D Elastance and Mobility Problems

Fuente: arXiv
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Autores principales: Broms, Anna, Barnett, Alex H., Tornberg, Anna-Karin
Formato: Preprint
Publicado: 2024
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author Broms, Anna
Barnett, Alex H.
Tornberg, Anna-Karin
author_facet Broms, Anna
Barnett, Alex H.
Tornberg, Anna-Karin
contents The method of fundamental solutions (MFS) is known to be effective for solving 3D Laplace and Stokes Dirichlet boundary value problems in the exterior of a large collection of simple smooth objects. Here we present new scalable MFS formulations for the corresponding elastance and mobility problems. The elastance problem computes the potentials of conductors with given net charges, while the mobility problem -- crucial to rheology and complex fluid applications -- computes rigid body velocities given net forces and torques on the particles. The key idea is orthogonal projection of the net charge (or forces and torques) in a rectangular variant of a "completion flow". The proposal is compatible with one-body preconditioning, resulting in well-conditioned square linear systems amenable to fast multipole accelerated iterative solution, thus a cost linear in the particle number. For large suspensions with moderate lubrication forces, MFS sources on inner proxy-surfaces give accuracy on par with a well-resolved boundary integral formulation. Our several numerical tests include a suspension of 10000 nearby ellipsoids, using 26 million total preconditioned degrees of freedom, where GMRES converges to five digits of accuracy in under two hours on one workstation.
format Preprint
id arxiv_https___arxiv_org_abs_2409_04215
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Method of Fundamental Solutions for Large-Scale 3D Elastance and Mobility Problems
Broms, Anna
Barnett, Alex H.
Tornberg, Anna-Karin
Numerical Analysis
Fluid Dynamics
65N80 (Primary) 76D07, 65D99, 35Q70 (Secondary)
G.1.8; J.2; I.6.5
The method of fundamental solutions (MFS) is known to be effective for solving 3D Laplace and Stokes Dirichlet boundary value problems in the exterior of a large collection of simple smooth objects. Here we present new scalable MFS formulations for the corresponding elastance and mobility problems. The elastance problem computes the potentials of conductors with given net charges, while the mobility problem -- crucial to rheology and complex fluid applications -- computes rigid body velocities given net forces and torques on the particles. The key idea is orthogonal projection of the net charge (or forces and torques) in a rectangular variant of a "completion flow". The proposal is compatible with one-body preconditioning, resulting in well-conditioned square linear systems amenable to fast multipole accelerated iterative solution, thus a cost linear in the particle number. For large suspensions with moderate lubrication forces, MFS sources on inner proxy-surfaces give accuracy on par with a well-resolved boundary integral formulation. Our several numerical tests include a suspension of 10000 nearby ellipsoids, using 26 million total preconditioned degrees of freedom, where GMRES converges to five digits of accuracy in under two hours on one workstation.
title A Method of Fundamental Solutions for Large-Scale 3D Elastance and Mobility Problems
topic Numerical Analysis
Fluid Dynamics
65N80 (Primary) 76D07, 65D99, 35Q70 (Secondary)
G.1.8; J.2; I.6.5
url https://arxiv.org/abs/2409.04215