Reynolds Equation 1

[Emmett04]

Hi everyone, I'm just drawing a blank here and can't remember the 1d reynolds equation..help?

 

[Montemayor]

Emmett04:

There must be over 100,000 references to Reynolds' famous classical relationship on such search engines like Google. It would certainly behoove you to use that convenient and ample avenue for such basic information. But, since I already started this post:

Re = Dvd/mu

D = pipe inside diameter
v = fluid's average velocity
d = fluid's density
mu = fluid's absolute viscosity

The result, as you should know, is dimensionless; so make sure all your units cancel out.

Art Montemayor
Spring, TX

 

[25362]

Dimensionless Reynolds number, as other famous dimensioneless numbers (Froude, Cauchy, Weber, and Euler), is the ratio of two forces.

In the case of the Re, it is the ratio of inertia forces to viscous forces: [ρ]L²V²/([μ]VL) = [ρ]VL/[μ] as given by Montemayor. Where for pipe flow:

V=velocity
[ρ]=density
L=diameter
[μ]= viscosity

In consistent units.

 

[25362]

Emmett04, kindly clarify whether you refer to the famous Reynolds number as explained by Montemayor, or to Reynolds one-dimensional equation for the "long bearing approximation" as in hydrodynamic lubrication.

 

[CARF]

And here the on-line freeware to calculate Reynolds and more:

http://www.carf-engineering.com/

Made by myself so it must be good ; )
CARF

 

[25362]

Still Emmett004 hasn't clarified whether he's after the Reynolds number equation or after the 1d Reynolds equation of hydrodynamic lubrication.

 

[rmw]

25362, From his profile, it looks like he logged in one time, started the thread, and hasn't been back since.

hmmm

rmw

 

[25362]

rmw, it also may be that after reading the satisfying answers Emmett004 called it a day.

 

[quark]

May be he was asking for an equation to know the length of a straight line(1d) that a Reynolds Pen can draw