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
joshuajim wrote:Hiker_01 wrote:
I'm not an expert, but I would guess that fluid dynamics are at play here. The air flowing around the truck/bus is traveling at a much faster speed than the rest of the air. Bernoulli's principle states that the faster a fluid (air) travels, the lower the pressure. This is how old time carburetors worked, and same reason why you have lift on airplane wings.
...but what about the fact that the air is already traveling faster around the trailer just like the passing vehicle? There shouldn't be any significant change.
When you are traveling down the road by yourself, same amount of air is flowing around both sides, so you have equal low pressures on both sides of your vehicle. Same with the semi - equal low pressures on both sides. When the semi is passing you, the air flow from the right side of the semi plus the left side of your vehicle must both flow through a limited space. More air (from both vehicles) combines with less space will cause a greater low pressure on your left side than right side, hence the pull towards the semi.
