Wind at High Speed

[Dr-Al]

No apparently there is nothing you can do about it so just stop the F.....g moaning about it!

Oh no Dr Al will be along soon to tell us about the low pressure area caused by a fat arse sat in a seat traveling at... blah blah blah blah

Nothing to do with fat arses. It's the Bernoulli principle at work. Air travelling past a surface exerts less pressure on the surface than air that is not moving. So, at speed, the air immediately outside the window is at a lower pressure than that inside the car so it pulls the window outwards.

There are 3 ways to cure the problem:

1) Make the window frame sit tighter to the door frame by adjusting the door. This will mechanically couteract the outward force.

2) Open the sunroof a crack. This will allow the lower pressure air passing over the top of the car to suck air out of the car, helping to reduce the pressure difference at the window.

3) Fit a deflector strip on the outside of the A-pillar. This will disrupt the airflow past the window, causing turbulence which will slow down the air and reduce the 'suction' effect.

Since 2 and 3 introduce extra drag, they should be avoided if you have a need for speed

There is a wite-up about the effect here:
http://en.wikipedia.org/wiki/Bernoulli%27s_principle

Short enough for you MCB, or should I have gone with the blah, blah, blah version?

[S4TAN]

So, at speed, the air immediately outside the window is at a lower pressure than that inside the car so it pulls the window outwards.

Wouldn't it be that the higher pressure air in the car 'pushes' the window out rather than the lower pressure air outside 'pulling' it out?

[ZeroK66]

ZeroK66 do you mean those with sunroof should open it a touch to stop the sucking out?

Satan, would Green Day do???

I believe if you have a sun roof the roof does not come in and cause the doors to open at the top. So I am one of the lucky few that does not suffer the doors openeing at speed.

That said though i have TERRIBLE wind noise due to a badly installed(I assume) windscreen. Will have that changed soon.

Cheers,
Leon

[Alps]

That said though i have TERRIBLE wind noise due to a badly installed(I assume) windscreen. Will have that changed soon.

Cheers,
Leon

Aha! So it isn't just another design fault then? I have a lot of noise coming in from, what seems to be, the top part of my wind screen. No draft though, funnily enough!

[Dr-Al]

So, at speed, the air immediately outside the window is at a lower pressure than that inside the car so it pulls the window outwards.

Wouldn't it be that the higher pressure air in the car 'pushes' the window out rather than the lower pressure air outside 'pulling' it out?

You're absolutely right

[MCB]

Short enough for you MCB, or should I have gone with the blah, blah, blah version?

No Dr Al only having a bit of fun!

[S4TAN]

You're absolutely right

Hey Al - just call me Dr-Science from now on!!!

I agree with you that out of your 3 solutions solution (1) is the best

P.S. A "fat arse......blah blah blah" version would've been more amusing!!

[Dr-Al]

@MCB - I know, so was I. I don't really care if people get sick of my 'essays' and dread seeing them. If only one reader finds them useful/interesting, then they have served their purpose.

@S4TAN - Sat for 5 mins trying to come up with a plausible explanation involving fat arses, but drew a blank. Sorry.

[S4TAN]

don't really care if people get sick of my 'essays' and dread seeing them.

I for one find them thoroughly enjoyable and informative mate - helps me dust off my old physics knowledge! Don't stop or there'll be a demon dispatched your way!

[ChipHazzard]

@S4TAN - Sat for 5 mins trying to come up with a plausible explanation involving fat arses, but drew a blank. Sorry.

well if you want the fat arse explanation here it is ..............

The larger the arse gernerally means a larger body mass thus reducing the internal cabin volume, therefore with the aircon producing a higher pressure there is less volume inside the cabine thus increasing the inside cabin pressure causing the over pressure to be released buy the lower pressure outside due to speed causing a vaccum pulling the tops of the doors open easier because of the higher pressure inside

thats enough science from me and the easy answer is go on a diet thus increasing the internal cabin volume and lowering the internal cabin pressure

[S4TAN]

therefore with the aircon producing a higher pressure

Aaargh! Step away from the air-con............(old joke)

[MCB]

The larger the arse gernerally means a larger body mass thus reducing the internal cabin volume, therefore with the aircon producing a higher pressure there is less volume inside the cabine thus increasing the inside cabin pressure causing the over pressure to be released buy the lower pressure outside due to speed causing a vaccum pulling the tops of the doors open easier because of the higher pressure inside

Nice one!

[philipwalker]

The larger the arse gernerally means a larger body mass thus reducing the internal cabin volume, therefore with the aircon producing a higher pressure there is less volume inside the cabine thus increasing the inside cabin pressure causing the over pressure to be released buy the lower pressure outside due to speed causing a vaccum pulling the tops of the doors open easier because of the higher pressure inside

Nice one!

Is that why I dont need much water in the bath?

[Dr-Al]

Is that why I dont need much water in the bath?

No - That's Archimedes' Principle but that's way off topic

[ChipHazzard]

philipwalker wrote:
Is that why I dont need much water in the bath?


No - That's Archimedes' Principle but that's way off topic

it would also mean less bubbles would be produced from the high speed wind in the bath ...............

has that got us back on topic