Saturated porous layers squeezed between parallel disks in enclosed cells

Abstract

Theoretical and experimental evidences show that high lift forces can be generated when a porous layer imbibed with a fluid is subjected to compression by a rigid and impermeable component in normal (approaching) relative motion. If the porous layer is soft enough to neglect its solid structure reaction to compression then the pressure increase can be entirely attributed to the flow resistance of the porous structure when the fluid is squeezed out. The mechanism is highly dependent on the variation of permeability with porosity at its turn variable with the rate of compression. Such a mechanism can be used for impact damping but realistic applications need to consider an enclosed system which keeps the squeezed fluid inside and allows for re-imbibition. The paper presents a simple analytical model for the effects produced in highly compressible porous layers imbibed with Newtonian liquids, during compression between two parallel rigid disks placed in enclosed cells with variable volume buffer, similar to a hydro-pneumatic accumulator.