Well-conditioned iterative schemes for mixed finite-element models of porous-media flows

摘要: Mixed finite-element methods are attractive for modeling flows in porous media since they can yield pressures and velocities having comparable accuracy. In solving the resulting discrete equations, however, poor matrix conditioning arise both from spatial heterogeneity medium fine grids needed to resolve that heterogeneity. This paper presents two iterative schemes overcome these sources of conditioning. The first scheme overcomes use grids. idea behind is spectral information about associated with version Darcy’s law precondition velocity employing a multigrid method solve mass-balance equations pressure or head. still exhibits slow convergence when permeability hydraulic conductivity highly variable space. second scheme, based on first, uses mass lumping Darcy thus requiring more work per i...