Flow and transport at high salinity

Salt has been selected as potential host medium for radioactive waste disposal in the F.R. of Germany. It is therefore important to study groundwater flow and radionuclide transport at high salt concentrations. In this case the flow and transport equations of brine are strongly coupled by fluid density and viscosity. As a first attempt to validate our models, we try to simulate a simple laboratory experiment. It has been carried out in the Geotechnique Laboratory of Delft University of Technology, The Netherlands, and is part of the international project INTRAVAL, (test case 13). Due to the experimental set-up our main subject of interest is the dispersive flux of brine. Since the simulations are very time consuming we restricted ourselves to one-dimensional cases. Results of different calculations with the finite-difference codes SWIFT and CHET will be represented. It will be shown that the Fickian ansatz is inadequate to describe dispersion at high concentrations or high concentration gradients, respectively. 6 figs., 2 tabs., 3 refs