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-   -   REYNOLDS NUMBER!!! (https://www.cfd-online.com/Forums/main/12494-reynolds-number.html)

Sze Hong Ng November 1, 2006 08:31

REYNOLDS NUMBER!!!
 
ok here is my problem, ive got to simulate the shockwaves over a NACA 0012 at mach 0.8 my problem resides in that basically i cannot find any documents which state Reynolds number, rho,u,l and mu to reference my stuff from I cant even start the project. Every report ive searched for states a Re and maybe 1 other parameter but nothing else! Please help me or tell me what are the benchmarks to start any flow simulation of a NACA 0012 from.

Thanks

ag November 1, 2006 10:29

Re: REYNOLDS NUMBER!!!
 
I don't understand your post. You say that you can't find documents giving Reynolds number, but that every report you've searched states Reynolds number. Assuming that you do have a Reynolds number and Mach number, then pick a temperature (atmospheric tables can be used if you want to simulate a particular altitude - this will also give you a density). Use the temperature to compute speed of sound, and use that to compute free-stream velocity. The temperature also gives the viscosity, if you use Sutherland's law or the power law. The length scale you choose depends on what you used to non-dimensionalize your equations of motion.

Sze Hong Ng November 2, 2006 06:47

Re: REYNOLDS NUMBER!!!
 
ok, what i meant was basically that i need to validate first CFX. I have the wing ordinates of a NACA0012, i need to test the wing at sea level, therefore i know the values of rho, u and mu. but i still have one value which im missing, Re and/or l the thing is that I need to know basically the reference wing chord length that people usually use, my lecturer tolme that it should be around 0.2...m but he's not sure.

ag November 2, 2006 07:49

Re: REYNOLDS NUMBER!!!
 
If you have the coordinates of the wing, then you have the chord length of the airfoil. Why not use that?

F.B.Tian November 5, 2006 18:35

Re: REYNOLDS NUMBER!!!
 
you can try this: Re=sqrt(\gama R T_0)Ma*D/(\niu)


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