GENERALIZED MULTISCALE FINITE ELEMENT METHOD FOR HIGHLY HETEROGENEOUS COMPRESSIBLE FLOW

In this paper, we study the generalized multiscale finite element method (GMsFEM) for single phase compressible flow in highly heterogeneous porous media. We follow the major steps of the GMsFEM to construct a permeability dependent offline basis for fast coarse-grid simulation. The offline coarse space is efficiently constructed only once based on the initial permeability field with parallel computing. A rigorous convergence analysis is performed for two types of snapshot spaces. The analysis indicates that the convergence rates of the proposed multiscale method depend on the coarse meshsize and the eigenvalue decay of the local spectral problem. To further increase the accuracy of the multiscale method, a residual driven online multiscale basis is added to the offline space. The construction of an online multiscale basis is based on a carefully designed error indicator motivated by the analysis. We find that an online basis is particularly important for the singular source. Rich numerical tests on typical 3D highly heterogeneous media are presented to demonstrate the impressive computational advantages of the proposed multiscale method.