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-   -   Why Stress-strain rate is equal to Vorticity in Boundary Layer? (http://www.cfd-online.com/Forums/main/111121-why-stress-strain-rate-equal-vorticity-boundary-layer.html)

aladdincham December 27, 2012 23:17

Why Stress-strain rate is equal to Vorticity in Boundary Layer?
 
Why Stress-strain rate is equal to Vorticity in Boundary Layer?
Hi friends,
Recently, I read some paper that said Stress-strain rate S is equal to Vorticity in Boundary Layer, Who can give me some expression about this.
Thx.

FMDenaro December 28, 2012 05:20

Quote:

Originally Posted by aladdincham (Post 399267)
Why Stress-strain rate is equal to Vorticity in Boundary Layer?
Hi friends,
Recently, I read some paper that said Stress-strain rate S is equal to Vorticity in Boundary Layer, Who can give me some expression about this.
Thx.


that is quite correct... consider a 2D flow over a flat plate, vorticity is z = du/dy - dv/dx, the stress at the wall is:

tau_wall = mu*du/dy|w = mu*(z + dv/dx)|w.

For a not permeable wall v=0 and tau_wall = mu*(z)|w


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