An experiment to verify the permeability of Hele‐Shaw cells

Abstract

A fluid layer sandwiched between two flat plates (Hele‐Shaw cell) has been assumed to model a saturated porous medium with permeability, d²/12, dependent only on the gap width, d. For situations where the properties of the porous matrix are important, such as thermal convection, the total cross‐section (y) of the sandwich should enter into the computation of permeability. To decide which of these approaches is valid, we observed the onset of convection in a Hele‐Shaw cell with constant gap width but spatially varying wall thickness. Convection begins in the thin‐walled section at a lower temperature difference than it does where the walls are thick. Our data confirm that d³3/12y is the permeability of Hele‐Shaw cells used to model thermal convection in porous layers.