I thought that the pressurized air would be forced out of the fuselage and stop when the pressure equalizes, i never heard of make up air
I should have explained it further.
If air is still flowing out of the aircraft due to a low pressure area at the hole in the fuselage it has to come from somewhere.
Since commercial airliners are well sealed, there would have to be an opening somewhat commensurate with the size of the hole in the fuselage.
One small, but interesting bit along these lines is the small frame-less hinged window cut into the side window of most of the low wing Piper single
It opens easily at flight speeds of 100 mph or so.
Sticking your fingers out of the small opening - about 4 x 6", the 6" being on the horizontal - you can feel the boundary layer, laminar airflow,
whatever you want to call it passing by.
Further out your fingers go, the stronger the airflow - obvious, I know, but it is indicative of airflow at high speeds.
Anyway, the little hinged window - that seats into a routed out opening and fits flush due to it's 45 or so degree outer edges and the matching
angled opening in the side window - does have a latch, but airflow keeps it shut with no problems.
There is a slight resistance when it's cracked open and that's due to the high pressure area on the inside of the fuselage trying to keep the window
There is no turbulence near the window and instead of admitting vent air as it would appear, what's happening is the opening is pulling in
"make-up" air from the not completely sealed fuselage area and exhausting it through the vent window.
All of which shows a low pressure area outside the aircraft and a high pressure area within although the pressure differentials are quite low.
Interestingly, somewhat the opposite happens with my 32 Ford roadster.
No fenders, hot rod engine etc.
When the top is on, a low pressure area is created within the cockpit area and air will bleed in through the gaps in the doors.
The air is hot due to the hood side panels are louvered and the hot engine compartment air is exhausted into the airflow along the car's body and
when it hits the low pressure area at the front and rear door gaps it get's sucked into the interior.
The temperature differentials between ambient and hot engine air are usually around 15-20 degrees F., and on very hot days it may run as high as 30
degrees F. different.
Granted, completely backward from the aircraft scenario, but interesting nevertheless.
The difference is probably due to the large side window openings and small ingress areas at the door gaps as well as the large speed differential
between a roadster running 70 mph and an airliner traveling 500 mph +.
As a small side note, the definition of a true roadster is, folding windshield, soft top and no roll-up windows.