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-   -   Skin friction coefficient (https://www.cfd-online.com/Forums/cfx/112265-skin-friction-coefficient.html)

 Anna Tian January 24, 2013 18:56

Skin friction coefficient

Hi,

I'm looking for the skin friction coefficient formula that CFX uses. But I didn't find it on user manual.

Could you please tell me which skin friction coefficient formula does CFX use?

Thank you very much!

 singer1812 January 25, 2013 11:51

tau_wall/(1/2*rho*Uinf^2)?

Not sure what you mean. Do you mean how do they get tau_wall?

 Anna Tian January 25, 2013 19:08

Quote:
 Originally Posted by singer1812 (Post 404031) tau_wall/(1/2*rho*Uinf^2)? Not sure what you mean. Do you mean how do they get tau_wall?
Yes. I guess it compute tau_wall by this

http://www.cfd-online.com/Wiki/Wall_shear_stress

But does it just set the fluid velocity at the wall as 0 then compute the (du/dy)_{y=0}? But how does it know du/dy at the wall(y=0) without knowing the wall shear stress in advance?

 singer1812 January 28, 2013 10:25

That can be a complicated discussion. I suggest looking at chapter 2 of the CFX Theory Guide.

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