A novel method to measure 3D permeability of highly porous materials*

Characterization of the complete three-dimensional (3D) permeability of porous materials is important for a range of industrial applications, from the manufacturing of composites to the extraction of oil and gas.  Previous studies have developed methods to estimate the 1D or 2D permeabilities of samples, but there are few methods that can completely characterize the permeability matrix that appears in the 3D generalization of the Darcy-Forchheimer relation.  To address this need, we have developed a constant-flow 3D permeameter that simultaneously measures the pressure drop across confined porous samples in all three directions (c.f., the more traditional constant-head or falling-head 1D systems). Pressure gradient measurements are translated into estimates for permeability using the Darcy-Forchheimer relation. We have also designed and 3D-printed a range of anisotropic porous lattices with pore sizes ranging from 0.6 mm to 2.0 mm and porosities >80% to test this new system.  The measured permeabilities show good agreement with predictions from numerical simulations.