Drivers don't create wind, so any wind will be 100% port.
Port's have the highest velocity near the tuning.
My screen shakes and blurs and I don't have anything behind mine, and mine is anchored to trusses and concrete (6inch screws and concrete nails), and my subs are mostly all sealed and the drivers are far from the screen too.
It's impossible to stop when the whole room is flexing. (Flexing 3 layers on each side, with the green-glue added.)
and now I've added another 13 subs since then... hehe!
My projector is also anchored to the trusses directly with more 6inch screws, and it still doesn't help...
[The goggles... they do nothing!] LOL
Here is an old vid showing what 8 of my subs and 25kW does:
That was when I just had B&W's, that's not even the DIY speakers or HzHorn or none of that beefier/louder stuff...
I will soon have 29 subs and 50-100kW up and running here.
(Yes I know... hurry up!