The steps for using the Darcy flow model are as follows:
Create a sub-task for the Darcy flow model.
Create a sub-task
Select the appropriate problem type from the Create a sub-task menu.
Darcy isothermal flow problem
or
Darcy non-isothermal flow problem
When prompted, specify a name for the sub-task.
Specify the region where the sub-task applies.
Domain of the sub-task
Set the material properties.
Material data
Define the parameters for the Darcy flow model.
Porous medium and fluid viscosity
-
Modification of Permeability
By default, permeability is a scalar (that is, the porous medium is isotropic), but you can specify a tensor permeability (that is, non-isotropic porous medium) by selecting Switch to tensor mode before selecting Modification of Permeability.
If the default scalar permeability is retained, you can simply enter a constant value for the permeability. If a tensor
is selected, you will need to enter the
Cartesian components of 
. In particular, for 2D flows, the components
and 
are requested, while, for 3D flows, the
components 
, 
, and 
are requested. Physical considerations
require that 
be positive-definite. Specify the fluid viscosity.
Modification of Fluid viscosity
Specify the void fraction of the porous medium.
Modification of Void fraction
For nonisothermal flows, specify the thermal conductivity for the solid (
in Equation 14–3).
Modification of Solid conductivity
(The thermal conductivity of the fluid,
, is specified as described in General Procedure.) For nonisothermal flows, specify the specific heat capacity for the solid (
in Equation 14–3).
Modification of Solid heat capacity
(The heat capacity of the fluid,
, is specified as described in General Procedure.) For nonisothermal flows, specify the density of the solid (
in Equation 14–3).
Modification of Solid density
(The heat capacity of the fluid,
, is specified as described in General Procedure.)
Specify any additional material properties required for nonisothermal flows. See General Procedure for details.
Define the flow boundary conditions.
Pressure boundary conditions
Select the boundary for which you want to set flow conditions.
Click Modify.
Select the boundary condition type you want to impose. For each boundary, there are three or four possible conditions. By default, Ansys Polydata imposes a zero pressure on all boundaries.
Choose Pressure imposed to specify the pressure on the boundary.
Pressure imposed
Select the appropriate specification method:
Select Constant to set a constant value for pressure.
Select Linear function of coordinates to specify a linear function of the form
for the pressure. Select Map from CSV (Excel) file to impose a pressure profile contained in a CSV file.
Select User-defined function to impose a pressure profile using a UDF.
Choose Normal velocity imposed to specify the normal velocity at the boundary.
Normal velocity imposed
Select the appropriate specification method:
Select Constant to set a constant value for normal velocity.
Select Linear function of coordinates to specify a linear function of the form
for the normal velocity. A
positive normal velocity represents an outflow.
Select Map from CSV (Excel) file to impose a normal velocity profile contained in a CSV file.
Select User-defined function to impose a normal velocity profile using a UDF.
Choose Wall to specify a zero-normal-velocity condition.
Wall
This is also the proper choice for an axis of symmetry.
Choose Interface between porous media (available only for interfaces between sub-tasks) to guarantee continuity of the pressure field and normal velocity across the interface
Interface between porous media
or choose Interface with fluid (also available only for interfaces between sub-tasks) to guarantee continuity of the normal velocity and the normal force across the interface. The tangential velocity will vanish on the fluid side.
Interface with fluid
Important: For a Darcy model, interfaces identify porous media that exhibit different material properties. All interfaces must therefore be fixed in space.
For more information on setting boundary conditions, see Boundary Conditions.
For nonisothermal flows, define the thermal boundary conditions.
Thermal boundary conditions
See Boundary Conditions and Problem Setup for details.