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-   -   Boundary condition convective boundary fluid-solid (http://www.cfd-online.com/Forums/openfoam/122446-boundary-condition-convective-boundary-fluid-solid.html)

Ricardo August 20, 2013 04:54

Boundary condition convective boundary fluid-solid
 
I would like use boundary condition (sufraceGradient=k*(A-Ainf)), where k is constant, A is value at surface of solid and Ainf is value of air. I used groovyBC, it works, but are here other posibilities?

I would like calculate surface value A from other fields, and groovyBC uses only average values of other field.

Thanks
Richard

Ricardo August 22, 2013 03:49

Hello, if i understood correctly fixedGradient is gradient between surface and central point.

code from "fixedGradientFvPatchField.H"
Code:

     
 
          x_p = x_c + \frac{\nabla(x)}{\Delta}
 
where
 
x_p      | patch values
x_c      | internal field values
\nabla(x)| gradient (user-specified)
\Delta  | inverse distance from patch face centre to cell centre

Is any possibility how to set gradient between surface and ambient?
Thanks
Richard

Ricardo September 2, 2013 04:15

Hello,
I used explicit scheme to calculate boundary values and then implicit scheme to calculate field centre values. It is conditionaly stable, but it works... :o

Does not exist easier method? :confused:
Something like using only half element on boundary, center point will be on boundary and will be solved with field values in matrix?
Thanks
Richard


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