7.6.20.6.3. Darcy

Syntax: Velocity [{of} SpeciesName] = Darcy [Gx = gx | Gy = gy | Gz = gz | Relative_To = relative_to]
Scope: Aria Material
Summary: This model is designed to provide the normalized fluid velocity within a matrix that itself may be moving. If the matrix phase has a velocity the fluid velocity returned will be in the lab frame. If not relative phase is provided, the matrix phase is assumed to have a velocity of zero. $u_g = v_r \phi - \frac{k_r}{\mu} \mathbf{K}_i( \nabla P_g - \rho_g \vec{g} )$