[Wasquid]

I rode the scooter up to Virginia Beach this Saturday and noticed an interesting phenomenon. The wind buffeting stops as I ride though tunnels.

On I-264, I enter a long tunnel lined in something like white tile, both lanes traveling in the same direction...and there is perfect quietness, very still air. As I exit the tunnel, the buffeting returns.

I returned home today; passed through the tunnel which carries traffic in the other direction, again it's quiet. I have no idea what is going on.

 

[NormanB]

I reckon it is the constrained dynamics. I am no aerodynamicist but my guess is the tunnel walls create an effect where the displaced air hugs it, forming a boundary layer and delays the 'collapse'. By the time the 'collapse' comes - you have moved out of range so do not feel the buffeting.

Lets have an aerodynamicist have a go at this one! :wink:

 

[Wasquid]

Norman,

I was wondering if all the traffic flowing in the same direction in the tight confines, could pump the air through the from the entrance to the exit and thus minimise the resistance a scooter experiences.

 

[NormanB]

Yeah could well be something like that, if the traffic flow is uni-directional then the air currents may be getting sorted in that way. In addition most tunnels have fans to assist exhaust fume extraction and if the designers have done their calculations correctly they would seek to harness that existing flow and boost it rather than set the fans up in opposition.

Just an opinion - surely we must have an expert here. Bruce is pretty clever - come on Bruce! :wink:

 

[ted clement]

I've been through the Baltimore tunnels with little to very sparse traffic and its the same....no wind, like riding in a vacuum. Such a unique feel, makes you want to keep on riding in a tunnel. The first time was quite a disconcerting sensation as it was totally unexpected. And you hear every sound from your motor that you've never heard before.

 

[Brian]

Even when traffic is light, a few vehicles going through a tunnel will get the air mass moving in the direction of traffic flow. Even when there is a time delay before the next car -- or bike -- enters, the air mass continues to flow exactly in the direction of travel for quite some time.

So when you enter the tunnel, any gusts and cross-winds are gone, and all you have is a mass of air moving along with you; sometimes at very nearly your speed. This creates the tunnel of silence effect.

Then, with the sound of your motor echoing off the walls and coming back at you, your senses are overloaded by the new sensation, and that also affects your awareness of what buffeting remains.

An interesting aside; stand at the exit of a small diameter but long tunnel sometime: when a big truck enters the tunnel you'll feel a gust at the exit long before the truck comes out. The truck becomes the "plunger" to the tunnel's "syringe," and the air is the "medicine."

 

[Wasquid]

Thank you for explaining that Brian.

It was strange to experience the effect you describe up close and personal on the scooter. I want to do it again.

 

[NormanB]

[snipped]
An interesting aside; stand at the exit of a small diameter but long tunnel sometime: when a big truck enters the tunnel you'll feel a gust at the exit long before the truck comes out. The truck becomes the "plunger" to the tunnel's "syringe," and the air is the "medicine."

However choose a safe spot and do not distract the truck driver - we do not want any lawsuits! :wink: He might think you are a 'jumper'!