Hydrodynamic mixing in two-phase flow through heterogeneous porous media at moderate capillary numbers

The subject of study is a two-phase flow through heterogeneous porous media. The capillary forces are taken into account. The medium heterogeneity causes the effect of mixing between fluids. At the macro scale, the effective description to this phenomenon is obtained by flow homogenization over heterogeneities. The phase mixing is manifested in two forms simultaneously: firstly the mixing causes the hydrodynamic dispersion effect with a nonlinear dispersion tensor; secondly the mixing determines a delay in the advective transport component. The cell problems are solved numerically. The structure of the dispersion tensor is studied as a function of saturation, transport velocity, viscosity ratio, medium heterogeneity and capillary number, which is the ratio between the capillary and the viscous forces. (authors)