Developing a modelling tool for density-driven flow in complex hydrogeological structures

Beginning in 1995, the codes $$\hbox {d}^{3}\hbox {f}$$d3f (distributed density driven flow) and $$\hbox {r}^{3}\hbox {t}$$r3t (radionuclides, reaction, retardation, and transport) for modeling density-driven groundwater flow and nuclide transport using UG toolbox are developed in the framework of several joint projects. During this time, the codes were substantially extended as well as numerically improved, and the development is still ongoing. Now, $$\hbox {d}^{3}\hbox {f}$$d3f and $$\hbox {r}^{3}\hbox {t}$$r3t are no longer restricted to modeling of porous media, they also may be used for fractured rock. These are powerful tools that are able to handle salt and heat transport, salt concentrations up to saturation and complex hydrogeological structures with high permeability contrasts.