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Boundary condition convective boundary fluid-solid

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Old   August 20, 2013, 04:54
Default Boundary condition convective boundary fluid-solid
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Richard
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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.

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Old   August 22, 2013, 03:49
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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?
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Richard
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Old   September 2, 2013, 04:15
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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...

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