Harmonic airflow in cabin when window down

[tjlyerly]

I've noticed that if I am driving with all the interior window up and my child, who likes to play with things, rolls down the rear passenger window - that it creates some kind of harmonic thumping in the cabin caused by the incoming airflow.

I've experienced this to a lesser extent in other cars but with the Leaf, it's like somebody put subwoofers right next to my ears with a frequency of about 200BPM. It is actually painful to my ears and I fly and SCUBA dive quite a bit so I'm not particularly sensitive to this kind of thing. It's not a big deal because I can just crack any of the other windows and it seems to disrupt the airflow enough that the thumping goes away. However, I can immediately tell if a rear window is down because I feel it immediately and it hurts and is actually quite noisy. It only seems to happen if I'm going >35mph, which makes sense. I assume this is because of the Leaf's uber streamlined airflow on the outside.

Curious if anyone else has experienced this.

 

[TomT]

They all do it. Most all cars I have owned have done it to one degree or another...

 

[adric22]

I posted about this a while back. I had never experienced it before in any other car. I accidentally rolled down a single rear window at about 50 mph and thought my eardrums would burst.

 

[ERG4ALL]

Same thing here. It is particularly annoying because we like to have a rear window down for our dog. When she has her head out the window the airflow is disrupted and the beat goes away. However, when she sticks her head back inside, it starts up again.

 

[TomT]

The more aerodynamic a vehicle is, the more likely this is to happen...

I posted about this a while back. I had never experienced it before in any other car. I accidentally rolled down a single rear window at about 50 mph and thought my eardrums would burst.

 

[bowthom]

Hello,
It's the reason some manufacturers add the little pop-up wing at the leading edge of the sunroof. It's creating a resonator chamber like blowing over a coke bottle opening.

 

[FairwoodRed]

This is pure speculation here, but I wonder if our quieter cars make us more sensitive to the volume level of the buffeting wind?

Kind of like when you are listening to the radio on the highway and just turn it off. Later in a parking lot you turn it back on and find that the volume is waaay too loud…

 

[tbleakne]

I just tried this, and the effect becomes annoying even at 40 mph. I would say frequency is very low, < 20 Hz, such that I feel it more than hear it.

 

[Levenkay]

Could be pure superstition, but I find that opening a diagonally-opposed window will usually kill the effect. For example, in order to have the driver's window halfway open or more, I need to crack the right rear passenger window a couple inches or so.

 

[mbender]

Amazing that I looked for this on the very day it was posted. I definitely get the incredibly noticable and annoying effect [since day 1], and there must be an elegant way for Nissan to "fix" it. (Other than providing a dog with every car )

 

[garsh]

Could be pure superstition, but I find that opening a diagonally-opposed window will usually kill the effect

I've also noticed this "beating" in most modern cars. And this is also how I've solved the problem. I don't necessarily open the diagonal window - I've found that cracking open either rear window will usually stop the effect.

 

[Nubo]

Amazing that I looked for this on the very day it was posted. I definitely get the incredibly noticable and annoying effect [since day 1], and there must be an elegant way for Nissan to "fix" it. (Other than providing a dog with every car )

It's called Helmholtz Resonance. As someone mentioned, the same effect as blowing air over a coke bottle. It's more prounounced in cars that are more aerodynamic, as the airflow is more laminar and closer to full speed near the suface of the car as compared to a non-aerodynamic vehicle. The solution is to "put another hole in the bottle". It's probably better for you to do that by cracking another window instead of Nissan leaving a permanent hole somewhere.

 

[OrientExpress]

Here is a link to what this is.

It is not unique to Nissan vehicles, ALL cars can do it. The only solution is to either roll down other windows, or close the offending (usually the rear) window.

 

[eclecticflower]

Could be pure superstition, but I find that opening a diagonally-opposed window will usually kill the effect

I've also noticed this "beating" in most modern cars. And this is also how I've solved the problem. I don't necessarily open the diagonal window - I've found that cracking open either rear window will usually stop the effect.

Yes, it has occurred on all of my cars and I resolve it by opening another window, usually the opposing rear window, because it creates airflow around & behind me. It's nothing to worry about.

 

[dsh]

If you roll down the opposite window i.e. front drivers side window if the rear passenger window is down, it will stop the 'thumping'.

 

[thehelix112]

I find it truly amazing that people would just be discovering this effect, and blaming the LEAF for it.

Dave

 

[mbender]

I find it truly amazing that people would just be discovering this effect, and blaming the LEAF for it.

Not just amazing (http://tinyurl.com/coowh7b), but truly amazing?
"Why, I'm shocked, shocked :shock: to find that rambling is going on in here! [...]
Everybody out at once!" click

 

[PatricioEV]

This is one of the main reasons I had a sunroof installed. I like the airflow, but hate the sound, of having a window open. The sunroof I installed is MUCH quieter than having a window open or even cracked.

http://www.mynissanleaf.com/viewtopic.php?p=196652