CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM Running, Solving & CFD (http://www.cfd-online.com/Forums/openfoam-solving/)
-   -   rhoSimplecFoam U-turn (http://www.cfd-online.com/Forums/openfoam-solving/92224-rhosimplecfoam-u-turn.html)

j-blindi September 6, 2011 19:14

rhoSimplecFoam U-turn
 
Hi,

I'm trying to run a simple U-turn with rhoSimplecFoam, like the squareBend in the tutorials but with other BCs, symmetryPlanes, different geometry,...
When I start rhoSimplecFoam I get a "floating point exception". I guess there's a problem with my start conditions, but I can't find the problem.

The case is pressure driven, so my start conditions are:

Inlet:
p: total pressure
u: zeroGradient
T: total temperatur
mut: calculated
k: turbulentIntensityKineticEnergyInlet
epsilon: turbulentMixingLengthDissipationRateInlet

Outlet:
p: pressure
u: zeroGradient
T: zeroGradient
mut: calculatedepsilon, k: zeroGradient

Is there a problem with these conditions? Otherwise I could post these files.

Greetings
Jason

j-blindi September 8, 2011 15:14

any ideas? I would be very thankful.

pcaste12 October 25, 2011 16:26

Hi Jason, I will not be a big help for you, I get identical problems!!
I make it works (a bit) when a change from pressure to velocity initial boundary. But I'm not very proud of it :(.
If you get any good result I will be interested.
Foamers:confused:?

Many thanks,
Pierre.

j-blindi October 25, 2011 19:42

Hi,

I changed my BCs so now I set a mass flux.
I also fixed some other problems (quite easy ones, but I'm still a beginner in OpenFOAM), that you can try.
My biggest problem was that the rho_min and rho_max in the fvsolution file were set to 0.1 and 1, what was far too low. Another problem was the initialisation of epsilon, lower values did a good job in my case.

Hope this'll help a little. I will think about more things I changed if it doesn't.

Best regards
Jason

PS: If I've got some time next week, I will try a pressure driven case again.

pcaste12 October 28, 2011 06:49

Hi,
Thanks for your reply, i will try the mass flow inlet.
What do you mean by:
"lower values did a good job "
I have calculated epsilon and it is arround 373, and on each iteration I got
...
bounding epsilon, min: -307.174 max: 338791 average: 949.244
...
and then
...
Time = 9

GAMG: Solving for Ux, Initial residual = 0.960776, Final residual = 0.0267023, No Iterations 1
GAMG: Solving for Uy, Initial residual = 0.912194, Final residual = 0.0457162, No Iterations 1
GAMG: Solving for Uz, Initial residual = 0.64707, Final residual = 0.0309212, No Iterations 1
GAMG: Solving for p, Initial residual = 0.319116, Final residual = 0.0313061, No Iterations 403
GAMG: Solving for p, Initial residual = 0.989979, Final residual = 0.0984753, No Iterations 472
time step continuity errors : sum local = 1.67649e+15, global = 3.27774e+14, cumulative = 3.27774e+14
rho max/min : 3 1.12128
#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::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#4 Foam::GAMGSolver::solveCoarsestLevel(Foam::Field<d ouble>&, Foam::Field<double> const&) const in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#5 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMa trix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#6 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libfiniteVolume.so"
#8 Foam::fvMatrix<double>::solve() in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/rhoSimplecFoam"
#9
in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/rhoSimplecFoam"
#10 __libc_start_main in "/lib/libc.so.6"
#11
in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/rhoSimplecFoam"
Exception en point flottant
...

Many thanks for your advise.
Pierre.

j-blindi October 29, 2011 06:31

Hi,

I'm not very familiar with turbulence.
In my case I had very high values for epsilon, but I chose lower values for my global field as initialisation and it worked fine. I still don't know why and if it's necessarry, but as long as it's just an initialisation....

Best regards,
Jason

pcaste12 October 29, 2011 17:21

Hi,
Anyway thanks for your answer, I gonna look at it deeper..;)
Pierre.


All times are GMT -4. The time now is 18:11.