A robust and efficient numerical model for analyses of density-dependent flow in porous media

A new computer code (MITSU3D) has been developed to simulate variable density-dependent flow in porous media. The techniques involve a control-volume discretization, Newton–Raphson linearization, and a flux limiter scheme. The assembled Jacobian matrices are solved by using preconditioned conjugate gradient-type methods employing a block-incomplete LU factorization and reduced system preconditioning. Numerical simulations involving contaminant migration in a two-dimensional cross-section show MITSU3D to be much faster and more robust than SUTRA. MITSU3D successfully avoids an “error-driven” contaminant plume instability in a coarse grid discretization and shows increased performance by a factor of five. The enhanced speed and robustness will enable us to examine much larger coupled problems than heretofore had been considered computationally practical.