Building a Robust Numerical Model for Mass Transport Through Complex Porous Media

When modelling complex physical problems model simplifications present an important step in a modelling procedure. One of the most common simplifications is dimensionality reduction. With dimensionality reduction the model becomes better manageable and consequently more robust. Mass transport modelling through porous media is typically characterized by complex physics and geometry. In the particular case of radionuclide transport modelling for radioactive waste repositories, an additional level of complexity, and thus uncertainty, originates from the long time frames involved. Performing a safety analysis of a radioactive waste disposal system requires therefore reasonable simplifications which enable us to model such complex system thereby minimizing the effect of uncertainties. In this work several examples, calculated by COMSOL Multiphysics 3.2, are selected to show the acceptable level of simplification to assure representative and yet robust modelling of radionuclide transport from a disposal facility.