Gas Phase Darcy Velocity in Porous Media#

Gas 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 gas phase, viz. the velocity of the gas phase due to gas-phase pressure gradients. This option is only available for POROUS_TWO_PHASE media types (cf. Media Type card). The velocity components appear in the output EXODUS II file as the nodal variables Darcy_Vel_g_0, Darcy_Vel_g_1 and Darcy_Vel_g_2.

The permissible values for this postprocessing option are:


Calculate the gas-phase Darcy velocity components and write to the output EXODUSII file.


Do not calculate the gas phase velocity components.


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

Gas phase Darcy velocity in porous media =yes

Technical Discussion#

The gas-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 \(\nu_g\) represents the Darcy flux, or Darcy velocity, in the gas phase, k is the permeability of the porous medium, \(k_g\) is the relative permeabilities for the gas and liquid phases respectively, \(\mu_g\) are the gas viscosity, \(p_g\) is the pressure in the gas phase, and g is the gravitational force vector. \(\rho_g\) is the density of the gas phase and is equal to the sum of the partial densities of air and solvent vapor,



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