Rear Window Ventilation / Air Flow Test

[alrashid2]

Hey guys, figured I'd do this little experiment today and post about it if anyone is curious. Never had a truck before so the rear window is a cool new feature for me! I had always read that air should ventilate out the rear window, but I smoked a cigar on the ride home last week and noticed the smoke puffing past my face and out the open driver's side front window, not out the back...

I taped a piece of red marking tape to the rear window and to my driver's side front windowsill, drove down the road at about 40 MPH, and did some little tests at varying levels of openness for both windows.

Interesting find. I found that regardless of how open or close the Front Driver's window and Rear window were, the ventilation was moving air from the outside, through the rear window into the cabin, then out the driver's front window. Exact opposite of what I always heard!

The only way I could get air to move out the rear window was by completely closing all the other windows and turning the HVAC air vents up. When I did that, the ribbon on the rear window moved outward instead of in, but just barely. When opening other windows, the ribbon moved into the cabin and strongly, getting more aggressive the more you opened the rear and front drivers windows.

Just figured I'd share! I do have a hard tonneau cover so not sure if that affects things. Thanks for reading.

Sponsored

 

[Khamsin]

When you're driving, air flowing over the cab separates behind it and creates a turbulent area in the bed. That turbulence can actually move air forward toward the cab in a slight vacuum. With the sliding rear window open, that air has an easy path into the cab — which is why you can get dust, leaves, or even exhaust coming in through the rear window even though you're moving forward.

It's basically the airflow around the truck creating a pressure difference and recirculation in the bed.

The wonders of fluid dynamics.