If I’m driving along and my windows are closed but my sunroof is in the tilt up position and the rear sliding window is open a couple of inches, how does the airflow get into the truck if I’m driving forwards? The gap on the sunroof faces backwards…
In:
Just turbulence. It makes basically small ripples in the air that then get pushed in the opening.
Put a long ribbon on a fan to see what that looks like.
Air pressure differences.
The top sunroof is pointed away from the flow of air, but that air is at a mostly normal pressure. The rear window is getting less pressure applied to it from the air outside, as it is trailing behind the vehicle. There will always be an area of lower pressure behind a moving vehicle, unless there’s some weird aerodynamics going on.
If you have two holes in a box, and one of those holes has less pressure around it that the other (from the outside), the air will flow from the first hole to the second one.
That’s basically what’s happening. Even though the sunroof is angled away from the wind, it still has more air pressure coming through it that the rear window does. That difference causes air to come in from the top, and flow through the back. You’re basically turning your car into a very complicated wind tunnel.
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