A fluid exchange interaction allows you to define the movement of fluid between a cavity and the surrounding environment or between two cavities. The fluid exchange interaction cannot be modified or deactivated in subsequent analysis steps. For a detailed discussion, see “Fluid exchange definition,” Section 11.5.3 of the Abaqus Analysis User's Guide.
To define a fluid exchange interaction:
From the main menu bar, select Interaction
Create.
Tip:
You can also create a fluid cavity interaction using the 
tool in the Interaction module toolbox.
In the Create Interaction dialog box that appears, do the following:
Name the interaction. For more information about naming objects, see “Using basic dialog box components,” Section 3.2.1.
Select Initial for the step in which the interaction will be created.
Select the Fluid exchange type of interaction.
Click Continue to close the Create Interaction dialog box.
Abaqus/CAE opens the Edit Interaction dialog box.
Toggle on the desired exchange definition, To environment or Between cavities.
Select the primary fluid cavity interaction, Fluid cavity interaction 1.
If you are defining an exchange between cavities, select Fluid cavity interaction 2.
Select a Fluid exchange property. If desired, click 
to create the interaction property; see “Defining a fluid exchange interaction property,” Section 15.14.5, for more information.
Enter a value for the Effective exchange area.
The effective exchange area represents the cross-sectional area of a pipe that the fluid is exchanged through.
Click OK to create the interaction and to close the editor.
Symbols that represent the fluid exchange interaction that you just created appear in the viewport. For more information, see “Understanding symbols that represent interactions, constraints, and connectors,” Section 15.10.
