Three-dimensional modeling of coupled flow and transport in porous media

Within the framework of safety assessment studies for the disposal of high level radioactive waste in subsurface salt formations, there is a need for powerful models that efficiently solve the highly non-linear and coupled governing equations for flow and transport of dissolved salt. These models are the basis for the prediction of the transport of radioactive material to the biosphere in case of unwanted release from a repository in the salt formation. A combined implicit/explicit model has been developed that solves the governing equations in an efficient way. A robust time step size estimator, which ensures stability of the solution, has been developed as part of the model. The solution method presents no convergence problems for the non-linear equations. The code is shown to be very well suited for vector and parallel processing. A speed up factor of approximately 30 in CPU time was observed when running the code in vector/parallel mode on 4 processors. This efficiency makes it possible to tackle real life three-dimensional problems.