Effective permeability
= Effective permeability
{title2=$k_{\rm eff}$}
An equivalent large-scale <permeability of a porous medium> relating imposed pressure drop to total <Darcy flux> through a heterogeneous sample. Parallel flow paths add conductances, whereas successive resistive segments add pressure drops. It depends on direction and boundary conditions; it need not be the arithmetic mean of the local permeabilities.