3.6.2011 Jan Brezina: Numerical coupling of Darcy flow on domains of different dimension Abstract Water in a granite rock is conducted by the complex system of fractures of various sizes. In our approach the small fractures are modeled by an equivalent permeable 3D continuum, while the preferential flow in the substantial geological dislocations and their intersections is considered as a flow on corresponding 2D manifolds and a flow on 1D lines respectively. We shall present several physical models of the coupling between dimensions and even more ways how to represent them on the discrete level in the spirit of Mortar and XFEM methods. For selected types of coupling, we shall show preliminary numerical tests of convergence order. Finally, we shall put forward several open theoretical questions and implementation issues that we are interested in. These include: parallelism, computational geometry, advection- diffusion-reaction equations, and discrete maximum principle.