car sides

blacklionboy

hi there,

I have just been wondering about this for a while.

If theres a car driving at highish speed. Would there lower pressure to the sides of the car and higher pressure going over the cars front? or vice versa?

thanks

congo_90

Lower pressure on the sides (front-mid section) and depending on how aerodynamic the car, the roof will have lower air pressure at high speeds approx 70km/h upwards. Just like a wing on an air-plane hence we get lift.

This is why in F1 racing you see a spoiler on the back, a front spoiler and minimum ground clearence with drag reducers underneath to essentially stop the car being a plane!

blacklionboy

so is that why a car's front corners are filleted quite a bit. to feed higher pressure from the middle of the car out to the lower pressure sides of the car?

congo_90

yeah. That and also to reduce drag cause by an uneven air flow from the leading edge of the car. If the car can smoothly penetrate the air it'll pass easier but if there were sharp corners on the front, miniture vortices would build up and at high speed this would affect the handling slightly. The main sections are the front, rear and under side.

The sides of a car are usually curved ever so slightly to assist the air passing by. You'll notice this by standing behind the car and looking along one side (from front to back)

The rear of a car plays as big of a role as the front as the air particles must meet at this point and this is where the force is strongest as the air has reached full speed.

By the way. I've only a basic knowledge of physics and the aerodynamics of objects from theory books used in flight schools etc.

Either way imagine running down the road with a piece of paper around your chest. It's easy as the air pushes by and makes its own path. now compare this to a 2x.5 metre section of plywood! it'd be a lot more difficult

imagine in this figure, the left is the ply wood and the right is the sheet. I'm not so concerned about the induced drag at the front but rather how the air moves through. hence the curve in the right hand sketch



All images taken from :http://www.bell-performance.co.uk

enda1

blacklionboy wrote: »

so is that why a car's front corners are filleted quite a bit. to feed higher pressure from the middle of the car out to the lower pressure sides of the car?

There is never one reason for anything in a car.

The frontal design has a big impact on frontal impact, aesthetics, pedestrian protection etc. etc.

Drag is only one factor.