Benchmarking Model Approaches for Thin Structures in a Porous Matrix

Open and closed faults, that are highly permeable or impermeable relative to the porous matrix in which they are embedded, show a strong influence on the fluid flow regime. The modelling of such thin structures may face severe problems, as high demands on storage requirement and execution time. Meshes require extremely fine resolution within the thin object and in its vicinity. The problems are much less severe, if the thin objects are represented in a lower dimension than the model domain. The resulting combined 2D/1D or 3D/2D models constitute a multi-physics approach. For basic benchmark problems we examine the accuracy of such mixed dimension approaches. We compare with the full dimensional model and with analytical solutions. Specific focus lies on the construction of streamlines, for which the streamfunction approach and the particle tracing technique are applied. Finally advantages and disadvantages of the various numerical approaches are summarized.