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.
The difference is when traveling alone, the air has an unlimited space to shift into, so the air only increases in speed by a small amount and it's balanced on both sides, so you don't feel a pull to one side or the other.
Once you get side by side, it is trapped between the two sides of the vehicles, so it must accelerate if the trucks hold the same speed. This imblances the forces. As a result, there is a lift force trying to pull the rigs together.
Trailer vs 5thW vs MH vs semi have slightly different feel because of the pivot point changes and weight but they all get pulled together.
Once past, you aren't actually pushed away, you are just reacting to the lack of force pulling you togther.
