Reynolds Number

[theycallmeebryan]

Hello fellow aero guros (sounds funny when it all rhymes)

I was wondering what you guys think would be a normal RE for sea level, 70*F temp, at 65mph, on earth.

Does RE=6063710 sound about correct for the above conditions with a 10ft chord?

I'm trying to use DesignFoil's wind tunnel simulation to try to figure out the best fairing for my Ninja 250. I understand that the ground plays an important role on the horizontal aerodynamics of a shape. However, since my ninja is more tall than wide, most of the air will be deflected to the sides and not over top (however, certainly its still significant).

[donee]

Hi ....bryan,

From : DreeseCODE Software, LLC an approximation for reynolds number is:

R.N. = 9360 * SPEED(in mph)*DIMENSION(in feet)

That dimension would be the length of the car.

[theycallmeebryan]

Originally Posted by donee

Hi ....bryan,

From : DreeseCODE Software, LLC an approximation for reynolds number is:

R.N. = 9360 * SPEED(in mph)*DIMENSION(in feet)

That dimension would be the length of the car.

Hmm... i spent hours reading through the manual last night and i must have missed that....

anywho, my RE number was darn close to that. thanks!

[aerohead]

Originally Posted by theycallmeebryan

Hello fellow aero guros (sounds funny when it all rhymes)

I was wondering what you guys think would be a normal RE for sea level, 70*F temp, at 65mph, on earth.

Does RE=6063710 sound about correct for the above conditions with a 10ft chord?

I'm trying to use DesignFoil's wind tunnel simulation to try to figure out the best fairing for my Ninja 250. I understand that the ground plays an important role on the horizontal aerodynamics of a shape. However, since my ninja is more tall than wide, most of the air will be deflected to the sides and not over top (however, certainly its still significant).

The thing to keep in mind,is that for road vehicles,the critical Reynolds number is achieved at about 20-mph and the turbulent boundary layer is firmly established along with Cd.This will remain constant up to about 250-mph,where compressibility begins (transonic flow) and drag typically rises as a function of Mach number.---------- If your software gives you the choice of selecting laminar or turbulent boundary layer,go with turbulent,unless you intend to ride at velocities below 20-mph.