In order to specify the same boundary condition on multiple windows, I created a composite region including all of the windows. If I want to have a pressure of 20000 Pa on each of the windows, should I specify an opening pressure boundary condition with value 20000 Pa or 20000*(number of windows) ? Cause it depends if CFX consider this composite region as a single region or if it consider the windows independently. Same question if you specify a mass flow.

Thank you

First of all, you don't necessarily need to create a composite region, just select all of your regions when you create the boundary condition.

Pressure doesn't scale with area, so the answer is NO for a pressure inlet boundary condition. If you specify the mass flow rate, it should be the total mass flow rate, which will be applied as a CONSTANT FLUX, so this will only work divide the mass flow evenly if you have the same area on each window. If the area varies and you want a constant mass flow through each you will need separate boundary conditions.

Regards, Robin