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Discussion Starter · #1 ·
At speeds above say 40mph if a rear window is opened there is quite a severe buffeting/pulsing of the air in the cabin which appears to be related to an opening/closing of the cabin air vent at the rear of the car.
I think other cars also suffer from this.
 

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Now, I was thinking qute the opposite with the Accord Tourer; total lack of buffeting (unlike most other cars). Shame the Civic's not the same... :(
 

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I've had that on several cars. The way to get over it is to open the rear window driver's side, and slightly open the front passenger window.;)
 

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I've had that on several cars. The way to get over it is to open the rear window driver's side, and slightly open the front passenger window.;)
I have had this on as many cars as I can remember. I have always found that opening another window slightly does the trick. I gues it is because it lets the incoming air back out rather than it buffet in the car.
 

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I've had that on several cars. The way to get over it is to open the rear window driver's side, and slightly open the front passenger window.;)
Common knowledge, but why should one have to?
 

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On Golf it's same thing. Open just rear windowd and it becomes unbearable. So, open front windows too a little.
 

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Common knowledge, but why should one have to?
Good question:confused: Maybe modern cars are so well sealed and if you are forcing air in it has nowhere to go
 

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Good question:confused: Maybe modern cars are so well sealed and if you are forcing air in it has nowhere to go
think that's it exactly :)

though would probably need a physics degree to work out why it seems to pulsate! :lol:

But yes, it's been the same as far back as I can remember - the TT was really bad for it!
 

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Or an aeroacoustics degree :eek:

From the Fluent website:

Wind buffeting, the noise and pulsating forces that are experienced when driving a car with the side windows open, has become a significant factor in the overall passenger experience in recent years. It is caused by an unstable shear layer that is established at the upstream edge of the window opening. Disturbances are shed from this location and travel along the side of the vehicle.
When they reach the rear edge of the window opening, a pressure wave is generated that propagates both inside and outside the passenger compartment. Outside the vehicle, this wave propagates both forward and backward along the side of the car. When the forward traveling wave reaches the front edge of the opening, it triggers another disturbance that moves back to the rear edge. This process is repeated many times every second and causes the shear layer to develop a characteristic buffeting frequency, which depends on the speed of the automobile and the geometry of the opening. Often the frequency is below the range that can be heard by human ears but it still can be felt by passengers as a pulsating wind force.
Wind buffeting can be detected using microphones, but the complicated pressure waves that are its cause are very difficult to measure. As a result, engineers in the past have had to wait until relatively late in the design process when prototypes become available to measure this phenomenon.
These measurements typically give them little or no information about what areas of the design are affecting wind buffeting and what could be done to reduce it. The only option is to modify and test the prototypes to see whether individual changes have any effect.
This process is so costly and time-consuming that it is difficult to identify changes that will improve the design.
 

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Discussion Starter · #10 ·
Pottsy,
Yes, I thought that was the problem.
Nice reply, you must have been a researcher in another life.
Regards, pcr.
 

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aerocoustics - what a great title! :D

good find sir - and what's more I even understood the answer :lol:



Well, kinda anyway :wink:
 

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I have a tip for you, don't, I repeat don't do as I did last evening on the way home from the Office, I put a rear window down and realised at around 30mph - 40 mph I got a buffeting noise, so I decided to see if it got better or worse as you went faster.

IT GETS WORSE! Only the sound kind of dissappears and all you can feel is a rhythmic pulsing as your eyes and ears begin to hurt. Had a bloody headache till nearly 9pm last night.

Dropping the second rear window a little helps, putting it all the way down seems to make it worse, cracking the front window helps though.

A tip I heard was that the speed of a car when this happens is called the flutter point, if you were to crackthe windscreen and have to come home without it, if you drive at this speed in a moderate rain shower, you would not get wet, the pulsing kind of pushes the rain back, so you keep your car dry, but then its a double edged sword, cos your eyes and ears start to bleed, you lose consciousness and crash horribly in to a river and the car gets wet anyway.

:confused: Head still hurts.................
 

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RR - love the descriptions! :lol:

The trick is definately to drop the window on the other side of the car by about an inch (or so, depending on speed) :)
 

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RR - love the descriptions! :lol:

The trick is definately to drop the window on the other side of the car by about an inch (or so, depending on speed) :)

Or possibly, keep them closed and use the climate control :)
 
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