Experimental characterisation of flow regimes in various porous media—I: Limit of laminar flow regime

Abstract

This work is part of a global study of flow regimes in porous media beyond Darcy regime. In view of determining the end of stable laminar regime in various porous media such as beds packed with spheres, stratified media and reticulated media, electrochemical micro-probes are inserted inside the medium and at the wall of test sections. Local instantaneous measurements of the limiting current intensity are implemented. Spectral analysis of the signal fluctuations enables an accurate determination of the end of stable laminar regime in the studied media. The comparison between internal measurements and those implemented at the wall of the cell shows that the latter are representative of the flow in the case of reticulated media but not in the case of packed beds of particles for which the use of internal probes is necessary. Results are expressed thanks to a pore Reynolds number Re p , based on a capillary representation of the porous media. Re p ≈180 characterises the end of the stable laminar regime in packed beds of particles presenting an isotropy in the plane perpendicular to the main direction of the fluid flow. A ‘laminarising effect’ is observed for synthetic foams. For each porous media tested, the percentage of viscous and inertial contributions in the pressure drop are given at the onset of fluctuations.