During experimental studies on the flow of water through consolidated sand filter beds, Henry D'Arcy, in 1856, formulated a law which boars his name. D'Arcy's Law states that the velocity of a homogenous fluid in a porous medium is proportional to the pressure gradient and inversely proportional to the fluid's viscosity. This law has been extended to describe, with certain limitations, the movement of other fluids including miscible fluids in consolidated rocks and other porous substances.
