Why do passing trucks suck instead of blow?
Nope, it's not the first line of a joke or a rhetorical question. I would expect a passing truck or bus to be pushing a wave of high pressure air in front and beside, but I've noticed time and agai...
Forum Discussion
Vulcan Rider wrote:
If you increase the amount of air in a (somewhat) confined space, the pressure goes up, not down.
The wake from each vehicle is already compressed somewhat; add the two together and the pressure is even higher.
At or near the front of the vehicles, I agree that the pressure will add up to a higher one but the high pressure at the front will cause a pressure gradient from front to back (where there is much lower pressure or even a vacuum). This in turn accelerates the air to a higher speed within the "tube" which reduces the static pressure throughout the space between the vehicles. This is why there's a bow wake pushing you away followed by the suction pulling you in when another vehicle passes you.
