Federico
Ansys Employee

Hello, 

First, what is your enclosure physically? If you want to have fluid escape away from the black box, you may set the boundaries to Pressure Outlets.

The warning messages about reverse flow simply means that:

  • flow is escaping a BC that is set to Inlet; or
  • flow is coming in through a BC that is set to outlet.

Unless you have strict requirements that flow should only come in/out through those boundaries, this may not be a problem.