Multiresolution operator decomposition for flow simulation in fractured porous media

Fractures should be simulated accurately given their significant effects on whole flow patterns in porous media. But such high-resolution simulations impose severe computational challenges to numerical methods in the applications. Therefore, the demand for accurate and efficient coarse-graining techniques is increasing. In this work, a near-linear complexity multiresolution operator decomposition method is proposed for solving and coarse graining flow problems in fractured porous media. We use the Discrete Fracture Model (DFM) to describe fractures, in which the fractures are explicitly represented as (n - 1)-dimensional elements. Using operator adapted wavelets, the solution space is decomposed into subspaces where DFM subsolutions can be computed by solving sparse and well-conditioned linear systems. By keeping only the coarse-scale part of the solution space, we furthermore obtain a reduced order model. We provide numerical experiments that investigate the accuracy of the reduced order model for different resolutions and different choices of medium. (C) 2019 Elsevier Inc. All rights reserved.