An efficient multiscale multigrid preconditioner for Darcy flow in high-contrast media

TL;DR

This paper introduces a multiscale multigrid preconditioner designed for efficient and robust solution of Darcy flow equations in highly heterogeneous porous media, demonstrating scalability and effectiveness in large-scale simulations.

Contribution

The paper presents a novel multigrid preconditioner that uses spectral problems to construct nested subspaces, improving solution efficiency for high-contrast Darcy flow problems.

Findings

Effective in handling media with high permeability contrast

Scales well up to 1024^3 resolution problems

Robust performance demonstrated in two-phase flow applications

Abstract

In this paper, we develop a multigrid preconditioner to solve Darcy flow in highly heterogeneous porous media. The key component of the preconditioner is to construct a sequence of nested subspaces $W_{\mathcal{L}}\subset W_{\mathcal{L}-1}\subset\cdots\subset W_1=W_h$. An appropriate spectral problem is defined in the space of $W_{i-1}$, then the eigenfunctions of the spectral problems are utilized to form $W_i$. The preconditioner is applied to solve a positive semidefinite linear system which results from discretizing the Darcy flow equation with the lowest order Raviart-Thomas spaces and adopting a trapezoidal quadrature rule. Theoretical analysis and numerical investigations of this preconditioner will be presented. In particular, we will consider several typical highly heterogeneous permeability fields whose resolutions are up to $1024^3$ and examine the computational performance of the preconditioner in several aspects, such as strong scalability, weak scalability, and robustness against the contrast of the media. We also demonstrate an application of this preconditioner for solving a two-phase flow benchmark problem.