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-   -   Poisson equation Cfx 4.4 (http://www.cfd-online.com/Forums/cfx/20414-poisson-equation-cfx-4-4-a.html)

Andrea June 3, 2004 05:29

Poisson equation Cfx 4.4
 
I need model the value of a user scalar V in the fluid domain (but indipendent by the fluid).

The associated equation is similar to the heat conducting in solid.

D=gradient

D.(k*D V)=S

How can I solve this equation in Cfx 4.4?

Thanks

Andrea


Jeff June 3, 2004 20:49

Re: Poisson equation Cfx 4.4
 
Set up an additional scalar (V) and under the DIFFERENCING SCHEME set NO CONVECTION.

Set values on all walls or leave alone for zero flux.

Unfortunately, inlets are a bit trickier as they will still try to convect or diffuse a zero value into the domain. I've solved this before in USRBCS by: * Loop over each cell in the inlet patch * examine the first adjacent cell to the boundary node * set the inlet to that value This, in essence, gives a zero flux condition on the INLET patch. You may have to do this on PRESSURE patches as well if there is inflow.

Good luck, Jeff

windhair August 17, 2004 06:34

Re: Poisson equation Cfx 4.4
 
I heard it is possible to solve the NO CONVECTION problem for inlets by using BCSEXT subroutine, but I have no idea about this, because it is not included in the document. How does it works?

Thanks


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