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 alessandro.zomparelli November 8, 2011 18:13

my first Natural Ventilation case with OpenFOAM

Hi to all!
I'm a newbie of CFD. I'm a student of Building Engineering/Architecture and I'm trying to simulate the natural ventilation of my building considering the wind and buoyancy effects using OpenFOAM. What do you think would be the best settings for boundary conditions? My mesh is like a box, with the faces not oriented in direction of the wind, because I need to simulate different direction cases.

I'm trying to find a good solution for setting fields U, p and p_rgh for my boundaries top, ground/building, north, south, east and west, but every time something goes wrong... someone can give me a hand? :confused:

thankyou

PS: I start from hotroom case of buoyancySimpleFoam tutorial. Is it right?

 alessandro.zomparelli November 9, 2011 06:14

Until now, I tried setting east side of my volume as inlet, the building and ground like a wall and top/west/north/south like outlet. The resulting U fields looks like:

Quote:
 dimensions [0 1 -1 0 0 0 0]; internalField uniform (-10 0 0); boundaryField { top { type zeroGradient; } west { type zeroGradient; } east { type fixedValue; value uniform (-10 0 0); } south { type zeroGradient; } north { type zeroGradient; } ground { type fixedValue; value uniform (0 0 0); } }
the p fields:

Quote:
 dimensions [1 -1 -2 0 0 0 0]; internalField uniform 101325; boundaryField { top { type fixedValue; value uniform 0; } west { type fixedValue; value uniform 0; } east { type zeroGradient; } south { type fixedValue; value uniform 0; } north { type fixedValue; value uniform 0; } ground { type buoyantPressure; } }
the p_rgh:

Quote:
 dimensions [1 -1 -2 0 0 0 0]; internalField uniform 101325; boundaryField { top { type fixedValue; value uniform 0; } west { type fixedValue; value uniform 0; } east { type zeroGradient; } south { type fixedValue; value uniform 0; } north { type fixedValue; value uniform 0; } ground { type buoyantPressure; } }
alphat:

Quote:
 dimensions [1 -1 -1 0 0 0 0]; internalField uniform 0; boundaryField { top { type fixedValue; value \$internalField; } west { type fixedValue; value \$internalField; } east { type fixedValue; value \$internalField; } south { type fixedValue; value \$internalField; } north { type fixedValue; value \$internalField; } ground { type alphatWallFunction; Prt 0.85; value uniform 0; } }
and epsilon:

Quote:
 dimensions [0 2 -3 0 0 0 0]; internalField uniform 0.01; boundaryField { top { type fixedValue; value \$internalField; } west { type fixedValue; value \$internalField; } east { type fixedValue; value \$internalField; } south { type fixedValue; value \$internalField; } north { type fixedValue; value \$internalField; } ground { type compressible::epsilonWallFunction; Cmu 0.09; kappa 0.41; E 9.8; value uniform 0.01; } }
nobody can give me some help?
This is the output message:
Quote:
 Create time Create mesh for time = 0 Reading g Reading thermophysical properties Selecting thermodynamics package hPsiThermo>>>> Reading field U Reading/calculating face flux field phi Creating turbulence model Selecting RAS turbulence model kEpsilon #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 in "/lib/libc.so.6" #3 Foam::compressible::RASModels::mutkWallFunctionFvP atchScalarField::calcMut() const in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libcompressibleRASModels.so" #4 Foam::compressible::RASModels::mutkWallFunctionFvP atchScalarField::updateCoeffs() in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libcompressibleRASModels.so" #5 Foam::fvPatchField::evaluate(Foam::UPstrea m::commsTypes) in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/buoyantSimpleFoam" #6 Foam::GeometricField::GeometricBoundaryField::evaluate() in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/buoyantSimpleFoam" #7 Foam::compressible::RASModels::kEpsilon::kEpsilon( Foam::GeometricField const&, Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&, Foam::basicThermo const&, Foam::word const&, Foam::word const&) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libcompressibleRASModels.so" #8 Foam::compressible::RASModel::adddictionaryConstru ctorToTable::New(Foam::GeometricField const&, Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&, Foam::basicThermo const&, Foam::word const&) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libcompressibleRASModels.so" #9 Foam::compressible::RASModel::New(Foam::GeometricF ield const&, Foam::GeometricField, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField const&, Foam::basicThermo const&, Foam::word const&) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libcompressibleRASModels.so" #10 in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/buoyantSimpleFoam" #11 __libc_start_main in "/lib/libc.so.6" #12 in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/buoyantSimpleFoam" Errore di virgola mobile

 alessandro.zomparelli November 9, 2011 10:22

well, I changed the value of pressure for both inlet and outlet conditions to fixedValue uniform 101325. Now the simulation run, but I can't understend very well the differences between p and p_rgh. It's correct to use the same settings for both pressures?

 behrouz April 1, 2015 10:16

hi to all.i'm a newbie of CFD.i'm try to run one case in tutorial that can simulate ventilation in simple room,so wich one case can be use?? and how i can run it
any refrence,guid,idea can help
tnx

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