Application of parallel aggregation-based multigrid to high resolution subsurface flow simulations

In this paper we assess the parallel efficiency issues for simulating single phase subsurface ow in porous media, where the permeability tensor contains anisotropy rotated with certain angles or severe discontinuity. Space variables are discretized using multi-points ux approximations and the pressure equations are solved by aggregation-based algebraic multigrid method. The involved issues include the domain decomposition of space discretization and coarsening, smoothing, the coarsest grid solving of multigrid solving steps. Numerical experiments exhibit that the convergence of the multigrid algorithm suffers from the parallel implementation. The linear system at the coarsest grid is solved and by various iterative methods and the experimental results show that the parallel efficiency is less attenuated when sparse approximate inverse preconditioning conjugate gradient is used.