(GRS 311) Representation of Inhomogeneities in the Flow and Transport Codes d³f and r³t

The codes d³f and r³t are well established for modelling density-driven flow and nuclide transport in the far field of repositories for hazardous material in deep geological formations. While originally intended to be applied to the overburden of a salt dome they were adapted to alternative host media such as crystalline rock or mudstone by including fractures into an otherwise porous medium. However, only discrete fractures or fracture networks with a rather limited number of fractures could be dealt with. Networks of smaller fractures – so-called background fractures – can easily consist of hundreds and thousands of significant individual fractures in a model domain and were therefore beyond the scope of d³f and r³t. One way to circumvent this problem is to replace a discrete fracture network with an equivalent porous medium. While this is a task in itself the codes had also numerically adapted to be to cope with the new methods. This report describes approaches and results of this work.