You can create a porous drag body force in an Abaqus/CFD analysis for flow through porous media.
To create or edit a porous drag body force:
Display the porous drag body force editor using one of the following methods:
To create a new porous drag body force, follow the procedure outlined in “Creating loads,” Section 16.8.1 (Category: Fluid; Types for Selected Step: Porous drag body force).
To edit an existing porous drag body force using menus or managers, see “Editing step-dependent objects,” Section 3.4.13. To edit the region to which the load is applied, see “Editing the region to which a prescribed condition is applied,” Section 16.8.4.
Click the arrow to the right of the Distribution field, and select the option of your choice from the list that appears:
Select Uniform to define a load that is uniform over the body.
Select an analytical field to define a spatially varying load. Only analytical fields that are valid for this load type are displayed in the selection list. Alternatively, you can click 
to create a new analytical field. (See Chapter 58, “The Analytical Field toolset,” for more information.)
In the Magnitude field, specify the value of the dimensionless porosity, 
(ratio of the fluid to the total volume of the porous medium).
If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click 
to create a new amplitude. (See Chapter 57, “The Amplitude toolset,” for more information.)
Click OK to save your data and to exit the editor.
