# Liquid Phase Darcy Velocity in Porous Media#

Liquid phase Darcy velocity in porous media = {yes | no}


## Description / Usage#

This post-processing option will lead to the explicit calculation and storage of the Darcy velocity components in the liquid phase, viz. the velocity of the liquid phase due to liquid phase pressure gradients. This option is available for all porous media types (cf. Media Type card). The velocity components appear in the output EXODUS II file as the nodal variables Darcy_Vel_l_0, Darcy_Vel_l_1 and Darcy_Vel_l_2.

The permissible values for this postprocessing option are:

 yes Calculate the liquid-phase Darcy velocity components and write to the output EXODUSII file. no Do not calculate the liquid phase velocity components.

## Examples#

This input example turns on calculation of the liquid phase velocity components:

Liquid phase Darcy velocity in porous media = yes


## Technical Discussion#

The liquid-phase Darcy velocity is given by the extended Darcy law, which accounts for the relative reduced flow due to the presence of another phase, viz.

Here $$v_l$$ represents the Darcy flux, or Darcy velocity, in the gas phase, k is the permeability of the porous medium, $$k_l$$ is the relative permeabilities for the liquid and liquid phases respectively, $$\mu_l$$ are the liquid viscosity, $$p_l$$ is the pressure in the liquid phase, and g is the gravitational force vector. $$\rho_l$$ is the density of the liquid phase.

## References#

GT-009.3: GOMA’s Capabilities for Partially Saturated Flow in Porous Media, September 1, 2002, P. R. Schunk