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-   -   traction free bc (http://www.cfd-online.com/Forums/cfx/82420-traction-free-bc.html)

alinik November 25, 2010 14:36

traction free bc
 
Hi everyone

Does anybody know haw can I introduce "traction free" BC at the outlet of my domain in CFX?

Regards

ghorrocks November 25, 2010 17:36

What is a traction free BC?

alinik November 25, 2010 23:18

this relation is called "traction"

T=-pI+2*mu*D,D=0.5*[grad(u)+grad(u)^T]

whenever it equals to zero, there is no traction or we can say it is traction free

alinik November 25, 2010 23:18

by the way "mu" is viscosity of the fluid

ghorrocks November 27, 2010 05:34

I assume u is the velocity field. What is p and I?

Can you explain what is the physical significance of this?

alinik November 27, 2010 07:03

P is pressure and I is the Identical matrix. it is said that this kind of bc does not affect the upstream flow conditions significantly

ghorrocks November 27, 2010 08:02

I see.

You may be able to do it as a CEL function on an outlet boundary condition with a CEL specified velocity or pressure, but you probably have to implement it in fortran.


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