Experimental and Numerical Determination of Interface Slip Coefficient of Fluid Stream Exiting a Partially Filled Porous Medium Channel

Stacks of parallel plates modeled as a standard fissure-type anisotropic porous medium are filled inside a rectangular channel up to half the cross section height. The interface slip coefficient $α$ for the isothermal laminar incompressible flow exiting this partially filled porous-medium channel is then determined using particle image velocimetry (PIV) experiments and numerical simulations. Required measurements of the Darcy velocity $uD$ on the porous-medium (PM) side, the local velocity $uf$⁠, and its gradient $∂uf/∂y$ on the clear-fluid (CF) side are performed across different length scales. The fissure-type porous-medium parameters are systematically varied in the porosity range $0.2≤φ≤0.95$ and flow direction permeability $10-6<K,m2<10-9$⁠. From the exit-velocity profile, the empirical slip coefficient $α$ is determined using a generalized relationship. When the measurements across the PM-CF interface are performed across a length scale equal to the representative elemental length (REL) of the porous media considered (i.e., equal to the sum of plate thickness (⁠$a$⁠) and gap (⁠$b$⁠)), the determined $α$ value is found to remain invariant.