Mesh Adaptation within the geochemistry-transport Alliances tool

Andra, CEA and EDF are conjointly developing a software platform for waste disposal simulations. The core of the tool for solute plume evaluation is the geochemistry transport coupling algorithm. Within Alliances, two geochemistry codes, PhreeqC and Chess, and three transport codes, Castem, Traces and Mt3D are available and interact within a sequential iterative algorithm for geochemistry transport coupling. Considering the waste disposal, one of the main problematic of a repository is to evaluate the alkaline perturbation in the host rock due to the cement interface with bentonite and clay. In order to deal with the heterogeneities and the various scales of the problem in two dimensions of space, a mesh adaptation method has been introduced to better deal with sharp interfaces. The adaptation algorithm will be described in details, pointing out its specificities due to the geochemistry treatment, especially concerning mineral interfaces. Numerical results will illustrate the algorithm performance for convection dominant and diffusion dominant problems.