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-   -   Airfoil - Critical Reynold? (https://www.cfd-online.com/Forums/main/178199-airfoil-critical-reynold.html)

Wingman October 1, 2016 16:35

Airfoil - Critical Reynold?
 
Hi,

I am trying to choose the most appropriate model for my airfoil / wing. The chord length is approximately 0.165m and my maximum velocity of 15 m/s. I'm using density of 1.225 kg/m3 and dynamic viscosity of 0.000018375 kg/ms.

Using Re = (rho*V*L)/(mu) = (1.225*15*0.165)/(0.000018375)
gives me Reynolds number of 165.000.

What is the Critical Reynolds number for Airfoils? Is there some rule of thumb for this? I'm leaning towards a Turbulent model... k-omega SST?

The wing I'm using has different shape than most NACA profiles and has a blunt edge.

https://t8wcbq-sn3302.files.1drv.com...0R0fQ/Wing.PNG

fluid23 October 3, 2016 17:21

Are you asking what Reynolds number boundary layer transition occurs?

truffaldino October 4, 2016 18:04

Quote:

Originally Posted by Wingman (Post 619980)
What is the Critical Reynolds number for Airfoils? Is there some rule of thumb for this? I'm leaning towards a Turbulent model... k-omega SST?

The wing I'm using has different shape than most NACA profiles and has a blunt edge.

https://t8wcbq-sn3302.files.1drv.com...0R0fQ/Wing.PNG

You will be wasting your tme with k-omega and any other turbulence modelling at such a low reynolds number. Use x-foil or xflr5: if there is no massive separation/bubbles, then your results will be much more accurate and you will easily and quickly see if there is separation, transition, where it happens etc.


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