I have a box or a lid that i chose the back face to be the fan, in an electronics enclosure, internal study. does this part have to match the size of the fan? for example the fan is a 1.5x15." square, if i draw the dummy fan block as a 1x1" square, is it going to matter for simulation?

what about multiple fans? if i chose one inlet fan and click on a couple different bodies, does it treat each of these as one fan or does it disprese the flow of one fan across all three bodies?