A flow mechanism for layering in a heterogeneous porous medium

The flow of a particle fluid mixture through a heterogeneous permeable material is studied with a view to obtaining characteristic fingerprints for the structures that such flows may exhibit. This flow has a variable density and behaves as a compressible fluid, with the compressibility derived from the variations of the local field variables. Both pressure-sensitive or speed-fluctuation-dependent rheologies are studied in the steady state and a speed-fluctuation-dependent material is studied in a time-dependent analysis. The salient findings are that for a pressure-sensitive material structures normal to the mean flow direction are obtained. For the speed-fluctuation-dependent rheology, the pressure structures are normal to the mean flow, whereas the density structures are aligned with the flow (fingering).Electronic Supplementary Material Electronic Supplementary Material is available in the online version of this article at .