HeatFlux in buoyantBoussinesq

ubaid · November 16, 2010, 15:41

Quote:

Originally Posted by David_010

Hi ubaid

snGrad is the gradient normal to a surface. The gradient term can be evaluated in different manners, and in the case of the temperature gradient at the wall, the heat flux expression q=k(DT/DX) employs the gradient normal to that wall, so snGrad is the correct way.

I suggest you to take a look to the Programmers Guide, I think it explains this better than me.

Hope it helps, regards

David

Hallo David,

Thanks a lot, i got what you meant. I will look at manual closely.

Best Regards,

sarahk · March 8, 2011, 10:35

Hey Foamers,

i just tried the turbulentHeatFluxTemperature bc in the buoyantBoussinesqPimpleFoam tutorial case with OF-1.7.1.
I exchanged all the kappaEff with alphaEff. Its reading all the files, starts the time loop and breaks up directly. i got a:

--> FOAM FATAL ERROR:
request for volScalarField unifrom from objectRegistry region0 failed
available objects ot type volScalarField are

do i need to add a field in createFields?
Thought its ok, when i just add a value in the 0/T file ...

Any suggestions?

Thanks in advance!

Sarah

Anne Lincke · August 17, 2011, 10:20

Dear Foamers,
can someone explain me why OF1.7 still uses

HTML Code:
- ghf*fvc::snGrad(rhok)*mesh.magSf()
instead of

HTML Code:
fvc::interpolate(rhok)*(g & mesh.Sf())
as it was used in the previous version OF1.6.
I do not understand why the gradient of the densitiy is used while in the equations I find in literature it has to be just the densitiy multiplied with the constant g.
Can someone help me? Is this still a bug or do I overlook something?
Also in the Wiki-Link
http://openfoamwiki.net/index.php/Bu...sinesqPisoFoam
they use the interpolated density instead of the surface normal gradient.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Wall with fixed heatFlux boundary condition	Martin Lorenz (Lorenz)	OpenFOAM Running, Solving & CFD	33	December 21, 2020 06:59
wallHeatFlux BC not constant after restart	eelcovv	OpenFOAM Running, Solving & CFD	26	May 25, 2011 00:11

March 8, 2011, 10:35		#22
sarahk New Member Sarah Köhler Join Date: Jun 2010 Location: Leoben Posts: 11 Rep Power: 16	Hey Foamers, i just tried the turbulentHeatFluxTemperature bc in the buoyantBoussinesqPimpleFoam tutorial case with OF-1.7.1. I exchanged all the kappaEff with alphaEff. Its reading all the files, starts the time loop and breaks up directly. i got a: --> FOAM FATAL ERROR: request for volScalarField unifrom from objectRegistry region0 failed available objects ot type volScalarField are do i need to add a field in createFields? Thought its ok, when i just add a value in the 0/T file ... Any suggestions? Thanks in advance! Sarah

August 17, 2011, 10:20		#23
Anne Lincke Senior Member Anne Gerdes Join Date: Aug 2010 Location: Hamburg Posts: 168 Rep Power: 16	Dear Foamers, can someone explain me why OF1.7 still uses HTML Code: - ghffvc::snGrad(rhok)mesh.magSf() instead of HTML Code: fvc::interpolate(rhok)*(g & mesh.Sf()) as it was used in the previous version OF1.6. I do not understand why the gradient of the densitiy is used while in the equations I find in literature it has to be just the densitiy multiplied with the constant g. Can someone help me? Is this still a bug or do I overlook something? Also in the Wiki-Link http://openfoamwiki.net/index.php/Bu...sinesqPisoFoam they use the interpolated density instead of the surface normal gradient.