Robin B.C=Mixed B.C ?

ksookhak · October 23, 2009, 13:41

Hi

Fro the Robin B.C:

dC/dy = a * C

where a is constant, C is scalar concentration and y is direction normal to the wall, How can I use the Mixed B.C? What will be the following terms?

refValue, refGradient, valueFraction and value?

Thanks in advance!

spl1504 · January 5, 2011, 08:37

Hi all,

some already posted the same question as I have here, but I could not find any answer that helped me.

I need to implement a Robin boundary condition of the form

c=a*dc/dx

with "a" being a constant, "x" the axis and "c" my volScalarField which is calculated by just one PDE (c(t,x,y,z)).
Can anyone give me a hint? I am not too familiar with programming in C++, so I have difficulties to understand the code of the OpenFOAM boundary conditions....

Maybe the answer is obvious for some of you, but unfortunately not for me, so I would really appreciate a help ...

Thanx

McCarra · January 10, 2011, 04:55

All types of boundary conditions for a volScalarField are:

advective
buoyantPressure
calculated
cellMotion
cyclic
directMapped
directionMixed
empty
fan
fixedFluxPressure
fixedGradient
fixedInternalValue
fixedPressureCompressibleDensity
fixedValue
freestream
freestreamPressure
inletOutlet
inletOutletTotalTemperature
mixed
oscillatingFixedValue
outletInlet
outletMappedUniformInlet
partialSlip
processor
rotatingTotalPressure
sliced
slip
surfaceSlipDisplacement
symmetryPlane
syringePressure
timeVaryingMappedFixedValue
timeVaryingMappedTotalPressure
timeVaryingTotalPressure
timeVaryingUniformFixedValue
timeVaryingUniformInletOutlet
totalPressure
totalTemperature
turbulentInlet
turbulentIntensityKineticEnergyInlet
uniformDensityHydrostaticPressure
uniformFixedValue
waveTransmissive
wedge
zeroGradient

In the thread "movingCone with time-dependent displacement" are also all the types por pointScalarField and volVectorField.

Maybe one of these types could help you!

benk · January 11, 2011, 09:50

I think the solution to your problem is in this post:
http://www.cfd-online.com/Forums/ope...condition.html

which I basically stole from this post:
http://www.cfd-online.com/Forums/ope...acianfoam.html

spl1504 · January 12, 2011, 04:11

So, unfortunately there seems to be no way to get around groovyBC when I am looking for a very general BC?!

I had a closer look at the other BCs but did not succeed in actually understand them, they seem very specific to me.

I downloaded groovyBC and followed the instructions on http://openfoamwiki.net/index.php/Contrib_groovyBC
but when I run the demo cases and use paraview for the visualisation, I always get a problem by seeing the velocity U, paraview shuts down directly. I tried the two versions of the libs hint, given on the website, but this did not change the problem. Does anyone have an idea what could be wrong?

(I use OpenFOAM-1.6.x).

Thank you very much..

benk · January 12, 2011, 10:33

I'm not sure about your paraview problems, maybe try posting/searching this thread: http://www.cfd-online.com/Forums/ope...burb-mesh.html

It seems as if groovyBC is just an interface for the mixed boundary condition which shows up in the list posted by McCarra above. So if you're good at C++ and don't want to use groovyBC, then you can try compiling your own boundary condition based on mixed.

October 23, 2009, 13:41	Robin B.C=Mixed B.C ?	#1
ksookhak New Member Kaveh Sookhak Lari Join Date: Oct 2009 Location: London Posts: 2 Rep Power: 0	Hi Fro the Robin B.C: dC/dy = a C* where a is constant, C is scalar concentration and y is direction normal to the wall, How can I use the Mixed B.C? What will be the following terms? refValue, refGradient, valueFraction and value? Thanks in advance!

January 5, 2011, 08:37	Robin BC	#2
spl1504 New Member sprenger Join Date: Aug 2010 Posts: 2 Rep Power: 0	Hi all, some already posted the same question as I have here, but I could not find any answer that helped me. I need to implement a Robin boundary condition of the form c=a*dc/dx with "a" being a constant, "x" the axis and "c" my volScalarField which is calculated by just one PDE (c(t,x,y,z)). Can anyone give me a hint? I am not too familiar with programming in C++, so I have difficulties to understand the code of the OpenFOAM boundary conditions.... Maybe the answer is obvious for some of you, but unfortunately not for me, so I would really appreciate a help ... Thanx

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January 10, 2011, 04:55		#3
McCarra Member Usit McCarra Join Date: Oct 2010 Posts: 51 Blog Entries: 2 Rep Power: 15	All types of boundary conditions for a volScalarField are: advective buoyantPressure calculated cellMotion cyclic directMapped directionMixed empty fan fixedFluxPressure fixedGradient fixedInternalValue fixedPressureCompressibleDensity fixedValue freestream freestreamPressure inletOutlet inletOutletTotalTemperature mixed oscillatingFixedValue outletInlet outletMappedUniformInlet partialSlip processor rotatingTotalPressure sliced slip surfaceSlipDisplacement symmetryPlane syringePressure timeVaryingMappedFixedValue timeVaryingMappedTotalPressure timeVaryingTotalPressure timeVaryingUniformFixedValue timeVaryingUniformInletOutlet totalPressure totalTemperature turbulentInlet turbulentIntensityKineticEnergyInlet uniformDensityHydrostaticPressure uniformFixedValue waveTransmissive wedge zeroGradient In the thread "movingCone with time-dependent displacement" are also all the types por pointScalarField and volVectorField. Maybe one of these types could help you!

January 11, 2011, 09:50		#4
benk Senior Member Ben K Join Date: Feb 2010 Location: Ottawa, Canada Posts: 140 Rep Power: 19	I think the solution to your problem is in this post: http://www.cfd-online.com/Forums/ope...condition.html which I basically stole from this post: http://www.cfd-online.com/Forums/ope...acianfoam.html

January 12, 2011, 04:11		#5
spl1504 New Member sprenger Join Date: Aug 2010 Posts: 2 Rep Power: 0	So, unfortunately there seems to be no way to get around groovyBC when I am looking for a very general BC?! I had a closer look at the other BCs but did not succeed in actually understand them, they seem very specific to me. I downloaded groovyBC and followed the instructions on http://openfoamwiki.net/index.php/Contrib_groovyBC but when I run the demo cases and use paraview for the visualisation, I always get a problem by seeing the velocity U, paraview shuts down directly. I tried the two versions of the libs hint, given on the website, but this did not change the problem. Does anyone have an idea what could be wrong? (I use OpenFOAM-1.6.x). Thank you very much..

January 12, 2011, 10:33		#6
benk Senior Member Ben K Join Date: Feb 2010 Location: Ottawa, Canada Posts: 140 Rep Power: 19	I'm not sure about your paraview problems, maybe try posting/searching this thread: http://www.cfd-online.com/Forums/ope...burb-mesh.html It seems as if groovyBC is just an interface for the mixed boundary condition which shows up in the list posted by McCarra above. So if you're good at C++ and don't want to use groovyBC, then you can try compiling your own boundary condition based on mixed.