Tomography-based determination of porosity, specific area and permeability of snow and comparison with measurements

- The direct comparison of physically measured and simulated permeability was unbiased.
- Inertial flow effects are very relevant even at low Reynolds numbers.
- A new parameterization for Darcy's law with 2nd and 3rd order corrections is given.

Micro-computed tomography (μ-CT) of snow replicas is used to characterize 34 snow samples by determining their specific surface area, porosity, effective permeability, anisotropy, and tortuosity. Their 3D geometrical representation obtained by μ-CT is used in direct pore-level simulations (DPLS) to numerically solve the governing mass and momentum conservation equations for fluid flow through porous media. It is found that inertial effects, given by a second and third order correction in Darcy's law, influence the air flow even at low Reynolds numbers. Correlations are derived for permeability, the Dupuit-Forchheimer coefficient and the third order coefficient of Darcy's law as a function of density and grain size. Comparison with the experimentally measured data yields good agreement and confirms the applicability of DPLS for determining the transport properties of snow.