A nonlinear multigrid method for inverse problem in the multiphase porous media flow

In this paper, we consider a parameter identification problem for the nonlinear convection-diffusion equation in the multiphase porous media flow. A nonlinear multigrid method is proposed for the recovery of permeability. This method works by dynamically adjusting the objective functionals at different grids so that they are consistent with each other, and ultimately reduce, the finest grid objective functional. In this manner, the nonlinear multigrid method can efficiently compute the solution to a desired fine grid inverse problem. Numerical results illustrate that the proposed multigrid approach both dramatically reduces the required computation and improves the reconstructed image quality. (C) 2017 Elsevier Inc. All rights reserved.