Volume Extract Tool
Use the 
Volume Extract
tool in the Analysis group on the
Prepare tab to create the volume that represents the internals of
a part or assembly (including meshes). You can create multiple fluid zones at the same
time if you have many seed faces selected.
Note: Selecting a mix of solid and faceted entities is not
supported.
A component named Volume containing the different fluid zone bodies named Volume is created in the Structure tree, and the bodies used to generate the volume are temporarily transparent when the volume is created.
Note: If an edge will be removed when you use the Volume Extract
tool, that edge will flash red and you will receive a warning message. This can
happen when you select a capping edge that will be removed when it is merged with
the rest of the model. The highlight identifies the problem so you can pick a
different edge.
This section contains the following topics: