Low Reynolds Modeling Lam Bremhorst
 

Hi everybody,

i am new in openFoam and at the moment also trying to make a low-Reynolds-Model work.
I use the LamBremhorstKE with the pisoFoam solver. I think that k and epsilon explode, and i get this error message:








/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.6 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 1.6-f802ff2d6c5a
Exec : pisoFoam
Date : Apr 12 2010
Time : 17:38:30
Host : itb15
PID : 13551
Case : /CFD/Moritz/ahmed_low_re_2
nProcs : 1
SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting turbulence model type RASModel
Selecting RAS turbulence model LamBremhorstKE
--> FOAM Warning :
From function GeometricField<Type, PatchField, GeoMesh>::readIfPresent()
in file /CFD/Daniel/src-openfoam/install/OpenFOAM-1.6/src/OpenFOAM/lnInclude/GeometricField.C at line 107
read option IOobject::MUST_READ suggests that a read constructor for field epsilon would be more appropriate.
^[[5;5~LamBremhorstKECoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
alphaEps 1.3;
}


Starting time loop

Time = 1e-07

Courant Number mean: 0 max: 0
DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 1.31903e-16, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 0, Final residual = 0, No Iterations 0
DICPCG: Solving for p, Initial residual = 1, Final residual = 0.0978004, No Iterations 297
time step continuity errors : sum local = 5.58285e-08, global = -1.88251e-10, cumulative = -1.88251e-10
DICPCG: Solving for p, Initial residual = 0.0402446, Final residual = 9.95978e-07, No Iterations 367
time step continuity errors : sum local = 8.99511e-11, global = 1.63882e-14, cumulative = -1.88235e-10
#0 Foam::error::printStack(Foam::Ostream&) in "/usr/local/OPENFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/usr/local/OPENFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib64/libc.so.6"
#3 Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/usr/local/OPENFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#4 void Foam::divide<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/usr/local/OPENFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::operator/<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<doub le, Foam::fvPatchField, Foam::volMesh> > const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/usr/local/OPENFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#6 Foam::incompressible::RASModels::LamBremhorstKE::c orrect() in "/usr/local/OPENFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#7 main in "/usr/local/OPENFOAM/OpenFOAM-1.6/applications/bin/linux64GccDPOpt/pisoFoam"
#8 __libc_start_main in "/lib64/libc.so.6"
#9 __gxx_personality_v0 in "/usr/local/OPENFOAM/OpenFOAM-1.6/applications/bin/linux64GccDPOpt/pisoFoam"
Gleitkomma-Ausnahme







I also ran the model with a coarser mesh, there it started calculating but k and epsilon went to -e12 to e12 and it finally crashed.
by the way, is it allowed that those values become negative?


Does anybody know if the LamBremhorst-Model is working in the actual version?

If yes, could you give me a hint, which initial conditions you use?
As boundary cond. i use

epsilon zeroGradient
k fixed value 0.000000001
nut calculated

all surfaces are defined as patch.

it would be great if somebody could explain experiences maybe already made.

all the best,
Moritz

#4 void Foam::divide<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/usr/local/OPENFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libincompressibleRASModels.so"

divison by zero, i.e initial and/or BC values of epsilon set to 0.

foam solver go booboo and complain, make unhappy noises and cry on the inside

thanks for your response, Niklas. I guess the problem is not that i have zeros, but that the epsilon is going up till the value gets too large. i can see in postprocessing, that first epsilon rises and k follows the next time step, so i guess something is wrong with the epsilon...
if somebody is able to use the model, could you post your settings (layer width, nu, U, bc an initials)? That would be a great help, i just dont find my mistake.

cheers,
moritz

Sorry to pick this thread up after 7 years (hehe). I was facing the same problem you mentioned when I used this model (my epsilon's values were growing too high).
Then I tried to use other model's results (LienCubic in my case) as a initial condition for k and epsilon and I've got better (but not perfect) results.

Also, this document,
http://www.diva-portal.org/smash/get...FULLTEXT01.pdf

compares some openfoam's low(and high) reynolds models. Moreover they got excelent results for the lambremhorst model. However, they use epsilon=0 as
a boundary condition at the wall even though the lambremhorst model specify
d epsilon/ dy =0


Hope this somewhat helps you or anyone.