Abstract
When rain pours over porous media, rain water tends to infiltrate their inside. In order to enable further infiltration, the air in the void of porous media has to be replaced with water. If the replacement between water and air is not smoothly implemented, water cannot seep into porous media as observed on river levees during heavy rainfall. This might be caused by the fact that the equilibrium of water with a relatively high density on top of air with a far lower density may be stable or weakly unstable in porous media. We have performed a linear stability analysis to study the Rayleigh-Taylor instability in porous media.
