Define where and how fast the flow motion is directed and set the boundary conditions to reduce boundary effects.

Flow Settings

The Flow Direction inside the structure will always be From Inlet to Outlet.

Determine if the Flow Motion is either Creeping Flow, which requires solving Stokes-Brinkman, or Fast Flow, for which Navier-Stokes-Brinkman is solved. How to choose between the two equations is explained here.

Inlet Material ID and Inlet Boundary Condition

Select the desired Inlet Material ID from the pull-down menu. Then, either define the average Pressure at the inlet or the Flow Rate at the inlet for the experiment. The selected ID must follow the conditions for inlet and outlet materials explained here.

Outlet Material IDs and Outlet Boundary Conditions

For Outlet Material IDs more than one material ID can be selected. In this case, they all have to follow the conditions for inlet and outlet materials explained here.

Set the Pressure for at least one outlet ID. It must be smaller than at the inlet, since pressure decreases from inlet to outlet. From the pull-down menus different units can be selected. If more than one outlet ID is selected, it is possible to define the Flow Rate for all outlet IDs but one.

If all outlet IDs are defined by Flow Rate, an error message appears.

Domain Boundary Conditions

Set the boundary conditions in all directions to be Periodic, Symmetric or No-Slip. More details on these settings can be found here. Since the structures used for the flow experiment usually have a large number of solid voxels at the boundaries and are not periodic, in most cases Symmetric boundary conditions should be used. If the simulation is done on only half or a quarter of the structure Symmetric boundary conditions must be used.