CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM (http://www.cfd-online.com/Forums/openfoam/)
-   -   wallShearStress (http://www.cfd-online.com/Forums/openfoam/90318-wallshearstress.html)

idrama July 7, 2011 03:58

wallShearStress
 
Hello Foamers,

I have a simple question about computing wall shear stresses: what is the difference between:

(1) tau_w=mu*grad(U) | y=0

and

(1) tau_W=mu [ grad(U)-grad(U)^T ] . n

where mu is the viscosity, U the velocity and n the surface normal.

Cheers

David* July 11, 2011 06:37

Hi Claus,
the second one makes no sense to me, why would you substract a transposed tensor from it's original? Where did you find this formula?
Regards,
David

idrama July 11, 2011 10:37

It can be found in several books about mechanics; there it is treated as the generalization of newtons law. The term even appears in the incompressible navier stokes equation.


All times are GMT -4. The time now is 13:24.