Darcy velocity
= Darcy velocity
{c}
{title2=$\mathbf u=\epsilon(\mathbf v_l-\mathbf v_s)$}
= Darcy flux
{c}
{synonym}
The Darcy velocity is liquid <volume flux> relative to the solid skeleton, divided by total cross-sectional area. If <porosity> is $\epsilon$, liquid velocity is $\mathbf v_l$, and skeleton velocity is $\mathbf v_s$, then $\mathbf u=\epsilon(\mathbf v_l-\mathbf v_s)$. Thus pore-fluid speed relative to the skeleton is $\mathbf u/\epsilon$, rather than $\mathbf u$.