
[Sponsors] 
February 6, 2014, 19:58 
Heat flux BC

#1 
New Member
Luca
Join Date: Feb 2014
Posts: 19
Rep Power: 11 
Hi,
I'm me again and I've another problem in my famous room. The room has inlet, outlet and a window. The other walls and floor are insulated. The window has a internal surface temperature of 18°C and I know the heat flux (218W/m^2) , yes out is cold. I don't know conductivity and thickness of the window, so I can't calculate the gradient. In my 0/T , how can I set the BC for the window? Is it enough if I just set 18°C as fixedValue? I tried also with: HTML Code:
type compressible::turbulentHeatFluxTemperature; heatSource flux; q uniform 218; kappa basicThermo; value uniform 305; HTML Code:
> FOAM FATAL IO ERROR: basicThermo is not in enumeration: 4 ( directionalSolidThermo fluidThermo lookup solidThermo ) What solution is better? How can I solve this error? Thanks 

February 10, 2014, 19:05 

#2 
New Member
Luca
Join Date: Feb 2014
Posts: 19
Rep Power: 11 
No answers?


February 11, 2014, 00:14 

#3 
Senior Member
Mohammad Shakil Ahmmed
Join Date: Oct 2012
Location: AUS
Posts: 136
Rep Power: 13 
You can add as the heat loss from the surface as Qloss, just add the term in the governing equation. I guess this is the easiest way.


February 16, 2014, 11:50 

#4 
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,969
Blog Entries: 45
Rep Power: 126 
Greetings to all!
@Luca: Have you tried using: Code:
kappa fluidThermo; Bruno
__________________


February 16, 2014, 11:55 

#5 
New Member
Luca
Join Date: Feb 2014
Posts: 19
Rep Power: 11 
Yes but it doesnt work i'll send the error later


February 16, 2014, 17:35 

#6 
New Member
Luca
Join Date: Feb 2014
Posts: 19
Rep Power: 11 
Ok i tried to solve some errors, but every time it give me another error ... and now i'm stuck.
Code:
Time = 1 DILUPBiCG: Solving for Ux, Initial residual = 0.000315202, Final residual = 1.81125e06, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.000383197, Final residual = 2.00909e06, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.000448386, Final residual = 3.1772e06, No Iterations 2 > FOAM FATAL ERROR: lookup of turbulenceModel from objectRegistry region0 successful but it is not a turbulenceModel, it is a kOmegaSST From function objectRegistry::lookupObject<Type>(const word&) const in file /home/opencfd/OpenFOAM/OpenFOAM2.2.2/src/OpenFOAM/lnInclude/objectRegistryTemplates.C at line 147. FOAM aborting #0 Foam::error::printStack(Foam::Ostream&) at ??:? #1 Foam::error::abort() at ??:? #2 Foam::compressible::turbulenceModel const& Foam::objectRegistry::lookupObject<Foam::compressible::turbulenceModel>(Foam::word const&) const at ??:? #3 Foam::temperatureCoupledBase::kappa(Foam::Field<double> const&) const at ??:? #4 Foam::compressible::turbulentHeatFluxTemperatureFvPatchScalarField::updateCoeffs() at ??:? #5 Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>::GeometricBoundaryField::updateCoeffs() at ??:? #6 Foam::fvMatrix<double>::fvMatrix(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::dimensionSet const&) at ??:? #7 at ??:? #8 at ??:? #9 __libc_start_main in "/lib/x86_64linuxgnu/libc.so.6" #10 at ??:? Aborted (core dumped) 

February 22, 2014, 11:35 

#7 
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,969
Blog Entries: 45
Rep Power: 126 
Hi Luca,
From the description you've made on the first post, could you please create a modified case using the tutorial "heatTransfer/buoyantSimpleFoam/hotRoom", using the same settings you're using and share it with us? I ask this because this way we (anyone reading this thread) would be able to more easily reproduce the same problem and try to find a solution. Otherwise, it will take considerable time for anyone else to setup the same case and attempt at reproducing the same problem. Best regards, Bruno
__________________


February 22, 2014, 11:50 

#8 
New Member
Luca
Join Date: Feb 2014
Posts: 19
Rep Power: 11 
This is the testcase, with a very very simple mesh
I tried to manipulate this case by myself..I'm a newbie so sure there will be stupid errors.. but everyone learn from their mistakes Thanks 

February 22, 2014, 12:54 

#9 
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,969
Blog Entries: 45
Rep Power: 126 
Hi Luca,
Attached is a working case, albeit not realistic at all. I simply took a hammer, a few nails and made it work without wobling This is the whole list of changes made... but very cryptic looking, aren't they: Code:
diff Nur Prova/0/T.org Prova2/0/T.org  Prova/0/T.org 20140216 21:33:08.000000000 +0000 +++ Prova2/0/T.org 20140222 16:28:44.768521049 +0000 @@ 22,11 +22,10 @@ { floor {  type compressible::turbulentHeatFluxTemperature; + type turbulentHeatFluxTemperature; heatSource flux; q uniform 10;  kappa fluidThermo;  kappaName fluidThermo; + alphaEff alphat; value uniform 305; } ceiling diff Nur Prova/constant/transportProperties Prova2/constant/transportProperties  Prova/constant/transportProperties 20140216 20:55:43.000000000 +0000 +++ Prova2/constant/transportProperties 20140222 16:30:03.320518263 +0000 @@ 21,6 +21,7 @@ TRef TRef [0 0 0 1 0 0 0] 298; Pr Pr [0 0 0 0 0 0 0] 0.73; Prt Prt [0 0 0 0 0 0 0] 0.85; +Cp0 1.3; CrossPowerLawCoeffs { diff Nur Prova/system/fvSchemes Prova2/system/fvSchemes  Prova/system/fvSchemes 20140216 21:26:43.000000000 +0000 +++ Prova2/system/fvSchemes 20140222 16:38:19.752500655 +0000 @@ 16,42 +16,40 @@ ddtSchemes {  default Euler; + default steadyState; } gradSchemes { default Gauss linear;  grad(p) Gauss linear;  grad(U) Gauss linear; } divSchemes {  default none;  div(phi,U) Gauss linearUpwind Gauss;  div(phi,k) Gauss upwind;  div(phi,epsilon) Gauss upwind;  div(phi,omega) Gauss upwind;  div((muEff*dev(T(grad(U))))) Gauss linear; + default none; + div(phi,U) bounded Gauss upwind; + div(phi,T) bounded Gauss upwind; + div(phi,k) bounded Gauss upwind; + div(phi,epsilon) bounded Gauss upwind; div((nuEff*dev(T(grad(U))))) Gauss linear; + div(phi,omega) bounded Gauss linear; } laplacianSchemes {  default none;  laplacian(nuEff,U) Gauss linear corrected;  laplacian((1A(U)),p) Gauss linear corrected;  laplacian(DkEff,k) Gauss linear corrected;  laplacian(DomegaEff,omega) Gauss linear corrected;  laplacian(DepsilonEff,epsilon) Gauss linear corrected;  laplacian(1,p) Gauss linear corrected; + default none; + laplacian(nuEff,U) Gauss linear corrected; + laplacian(Dp,p_rgh) Gauss linear corrected; + laplacian(alphaEff,T) Gauss linear corrected; + laplacian(DkEff,k) Gauss linear corrected; + laplacian(DepsilonEff,epsilon) Gauss linear corrected; + laplacian(DREff,R) Gauss linear corrected; + laplacian(DomegaEff,omega) Gauss linear corrected; } interpolationSchemes { default linear;  interpolate(U) linear; } snGradSchemes @@ 62,7 +60,7 @@ fluxRequired { default no;  p; + p_rgh ; } // ************************************************************************* // diff Nur Prova/system/fvSolution Prova2/system/fvSolution  Prova/system/fvSolution 20140216 21:24:56.000000000 +0000 +++ Prova2/system/fvSolution 20140222 16:36:54.124503691 +0000 @@ 24,58 +24,52 @@ solvers {   p PCG + p_rgh {  maxIter 1000;  preconditioner DIC;  tolerance 1e06;  relTol 0;  }; + solver PCG; + preconditioner DIC; + tolerance 1e08; + relTol 0.01; + }  U PBiCG  {  preconditioner DILU;  tolerance 1e05;  relTol 0;  };  k PBiCG  {  preconditioner DILU;  tolerance 1e05;  relTol 0;  };  omega PBiCG + "(UTkepsilonRomega)" {  preconditioner DILU;  tolerance 1e05;  relTol 0;  };  epsilon PBiCG  {  preconditioner DILU;  tolerance 1e05;  relTol 0;  };  + solver PBiCG; + preconditioner DILU; + tolerance 1e05; + relTol 0.1; + } } SIMPLE {  nNonOrthogonalCorrectors 2; pRefCell 0;  pRefValue 0; + nNonOrthogonalCorrectors 0; + pRefCell 0; + pRefValue 0; + residualControl + { + p_rgh 1e2; + U 1e4; + T 1e2; + + // possibly check turbulence fields + "(kepsilonomega)" 1e3; + } } relaxationFactors {  p 0.3;  U 0.7;  k 0.7;  epsilon 0.7;  omega 0.7; + fields + { + p_rgh 0.7; + } + equations + { + U 0.3; + T 0.5; + "(kepsilonR)" 0.7; + } }  // ************************************************************************* //
Best regards, Bruno
__________________


February 22, 2014, 12:59 

#10 
New Member
Luca
Join Date: Feb 2014
Posts: 19
Rep Power: 11 
Thanks a lot!!
Later I will try .. even if for my thesis I'm using another set of BC and, compared to the experimental result, it seems quite good. Then in the conclusions I will talk about this (probably better) possibility! Thanks again! 

Thread Tools  Search this Thread 
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Total heat transf. rate vs Total surface heat flux  Renato Sousa  FLUENT  1  April 14, 2020 04:27 
Wall Heat Flux & Temperature  Greg Perkins  FLUENT  10  November 20, 2015 10:32 
Enforce bounds error with heat loss boundary condition at solid walls  Chander  CFX  2  May 1, 2012 21:11 
Negative Heat Flux  shashank312  FLUENT  3  December 9, 2011 18:00 
CFX  wall heat flux  divarano  CFX  2  December 4, 2006 17:14 