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-   -   FixedGradient BC update (http://www.cfd-online.com/Forums/openfoam-solving/59601-fixedgradient-bc-update.html)

stefan82 June 15, 2007 09:03

Could somebody explain to me,
 
Could somebody explain to me, how I can implement a fixedGradient boundary condition looking like this:

d(u(i+1))/dn = f(u(i)) with time index i.

In words: I'd like to get the value of the normal derivation of u(i+1) from a function f depending on u(i), but as far as I've found out till now, fixedGradient sets the gradient to a constant value. Is it possible to replace the constant value by a function calculated during the iteration process? And if yes, could somebody give me a hint or an example how I could do this?

Many thanks in advance!!!

coops June 17, 2007 21:08

Hello Stefan, It is possibl
 
Hello Stefan,

It is possible the gradient to a value that is calculated during the iteration process. Have you had a look at the fixedFluxBuoyantPressure boundary condition.
(/home/you/OpenFOAM/OpenFOAM-1.4/src/finiteVolume/fields/fvPatchFields/derivedFv PatchFields/fixedFluxBuoyantPressure
)

I hope this helps.

Shaun

stefan82 June 19, 2007 07:00

Hello Shaun, thank you very
 
Hello Shaun,

thank you very much for your reply - I'll check it out ;-)

best regards, Stefan

prapanj April 25, 2009 08:36

try GroovyBC
 
Hi Stefan,

Search for groovyBC. That is an external package that lets you set boundary conditions based on any formula you want. I am sure it will help your case. Easy to install too..

Prapanj

ivan_cozza April 28, 2009 03:10

Hi to evrybody!
Is there any inplementation of this time dependent fixed value for the 1.5 release?
Tanx


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