The rotation of a vertical interface in a porous medium
Arnold Verruijt · Water Resources Research · 1980
A solution is given of the problem of the simultaneous flow of two different fluids in a vertical plane, separated from each other by a vertical interface. It is shown that the viscosities of the two fluids influence the motion of the interface only through their average value. A simple formula for the rotation of the interface is derived in terms of the relative density difference.