FixedGradient BC update

stefan82 · June 15, 2007, 09:03

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

best regards, Stefan

prapanj · April 25, 2009, 08:36

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

June 15, 2007, 09:03	Could somebody explain to me,	#1
stefan82 New Member Stefan Furtlehner Join Date: Mar 2009 Location: Vienna, Austria Posts: 7 Rep Power: 17	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!!!

June 17, 2007, 21:08	Hello Stefan, It is possibl	#2
coops Member Shaun Cooper Join Date: Mar 2009 Posts: 54 Rep Power: 17	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

June 19, 2007, 07:00	Hello Shaun, thank you very	#3
stefan82 New Member Stefan Furtlehner Join Date: Mar 2009 Location: Vienna, Austria Posts: 7 Rep Power: 17	Hello Shaun, thank you very much for your reply - I'll check it out ;-) best regards, Stefan

April 25, 2009, 08:36	try GroovyBC	#4
prapanj Senior Member Prapanch Nair Join Date: Mar 2009 Location: Bangalore, India Posts: 105 Rep Power: 17	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

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April 28, 2009, 03:10		#5
ivan_cozza Senior Member Ivan Flaminio Cozza Join Date: Mar 2009 Location: Torino, Piemonte, Italia Posts: 210 Rep Power: 18	Hi to evrybody! Is there any inplementation of this time dependent fixed value for the 1.5 release? Tanx