Graph-Based Meshfree Multi-scale Coarse Space Approximation for Two-Level Schwarz Methods

Fuente: arXiv
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Auteurs principaux: Liu, Yucheng, Yeung, Tak Shing Au, Chung, Eric T., See, Simon
Format: Preprint
Publié: 2026
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author Liu, Yucheng
Yeung, Tak Shing Au
Chung, Eric T.
See, Simon
author_facet Liu, Yucheng
Yeung, Tak Shing Au
Chung, Eric T.
See, Simon
contents Efficient simulation of Darcy flow in highly heterogeneous porous media requires iterative solvers that remain robust under large permeability contrasts and mixed boundary conditions. Spectral coarse spaces in two-level overlapping Schwarz methods provide such robustness, but their practical use is often limited by an expensive setup phase dominated by many local generalized eigenvalue solves. We propose a purely algebraic, coarse-space approximation that avoids these repeated local eigensolves by using a graph neural network operating on the system-matrix graph. On the analysis side, we introduce a coefficient-weighted subspace-distance measure to quantify the discrepancy between the approximated and target local multiscale coarse spaces, and we derive a condition-number bound for the resulting preconditioned operator in terms of this distance. This bound yields a principled supervised-training objective and links learning error to solver performance. Numerical experiments on 2D and 3D high-contrast Darcy systems with varying mixed boundary conditions demonstrate that the proposed approach substantially reduces setup cost and improves end-to-end time-to-solution, while preserving robust convergence across the tested contrasts and boundary configurations.
format Preprint
id arxiv_https___arxiv_org_abs_2603_26149
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Graph-Based Meshfree Multi-scale Coarse Space Approximation for Two-Level Schwarz Methods
Liu, Yucheng
Yeung, Tak Shing Au
Chung, Eric T.
See, Simon
Numerical Analysis
65N08, 65N15, 65N55
Efficient simulation of Darcy flow in highly heterogeneous porous media requires iterative solvers that remain robust under large permeability contrasts and mixed boundary conditions. Spectral coarse spaces in two-level overlapping Schwarz methods provide such robustness, but their practical use is often limited by an expensive setup phase dominated by many local generalized eigenvalue solves. We propose a purely algebraic, coarse-space approximation that avoids these repeated local eigensolves by using a graph neural network operating on the system-matrix graph. On the analysis side, we introduce a coefficient-weighted subspace-distance measure to quantify the discrepancy between the approximated and target local multiscale coarse spaces, and we derive a condition-number bound for the resulting preconditioned operator in terms of this distance. This bound yields a principled supervised-training objective and links learning error to solver performance. Numerical experiments on 2D and 3D high-contrast Darcy systems with varying mixed boundary conditions demonstrate that the proposed approach substantially reduces setup cost and improves end-to-end time-to-solution, while preserving robust convergence across the tested contrasts and boundary configurations.
title Graph-Based Meshfree Multi-scale Coarse Space Approximation for Two-Level Schwarz Methods
topic Numerical Analysis
65N08, 65N15, 65N55
url https://arxiv.org/abs/2603.26149