A novel block non-symmetric preconditioner for mixed-hybrid finite-element-based Darcy flow simulations

In this work, we propose a novel block preconditioner, labeled Explicit Decoupling Factor Approximation (EDFA), to accelerate the convergence of Krylov subspace solvers used to address the sequence of non-symmetric systems of linear equations originating from flow simulations in porous media. The flow model is discretized blending the Mixed hybrid finite element method for Darcy's equation with the Finite volume scheme for the mass conservation. The EDFA preconditioner is characterized by two features: the exploitation of the system matrix decoupling factors to recast the Schur complement and their inexact fully-parallel computation by means of restriction operators. We introduce two adaptive techniques aimed at building the restriction operators according to the properties of the system at hand. The proposed block preconditioner has been tested through extensive experimentation on both synthetic and real-case applications, pointing out its robustness and computational efficiency. (C) 2021 The Author(s). Published by Elsevier Inc.

Automated summary

This work introduces a novel block preconditioner EDFA to accelerate the convergence of Krylov subspace solvers for non-symmetric linear systems. The flow model is discretized using a blend of finite element and finite volume schemes. Experimental results demonstrate the robustness and computational efficiency of the proposed preconditioner.