[sErik]

Hi Foamers,

I have some trouble with buoyantBoussinesqPisoFoam. I like to run the solver on a tube with several curves.
I tried to adapte the hotRoom tutorial BC on my case and I took the same files for fvSolution and fvSolvers.
Actually I have three patches - inlet, outlet and wall.

My BCs are:
inlet

type inlet;

p: type fixedValue;
rho rhok;
value niform 7638;
U: type fixedValue;
value uniform (1.7466 0 0);
T: type fixedValue;
value uniform 383;
alphat: type zeroGradient;
k: type fixedValue;
value uniform 0.375;
epsilon: type fixedValue;
value uniform 14.85;

outlet

type outlet;

p: type zeroGradient;
rho rhok;
value niform 7638;
U: type zeroGradient;
T: type zeroGradient;
alphat: type zeroGradient;
k: type zeroGradient;
epsilon: type zeroGradient;

wall

type wall;

p: type buoyantPressure;
rho rhok;
value uniform 0;
U: type zeroGradient;
T: type zeroGradient;
alphat: type compressible::alphatWallFunction;
Prt 0.85;
value uniform 0;
k: type kqRWallFunction;
value $internalField;
epsilon: type epsilonWallFunction;
value uniform 14.855;

However, I get this error message

Create time

Create mesh for time = 0


Reading g
Reading thermophysical properties

Reading field T

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Creating turbulence model

Selecting RAS turbulence model kEpsilon
kEpsilonCoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
sigmaEps 1.3;
}

Courant Number mean: 0 max: 6.67404

Starting time loop

Time = 0.001

Courant Number mean: 0 max: 6.67404
DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 8.70676e-06, No Iterations 8
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 9.14117e-06, No Iterations 12
DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 3.47137e-06, No Iterations 8
DILUPBiCG: Solving for T, Initial residual = 1, Final residual = 4.04506e-06, No Iterations 10
DICPCG: Solving for p, Initial residual = 1, Final residual = 0.0983862, No Iterations 49
time step continuity errors : sum local = 0.0703709, global = -0.0110895, cumulative = -0.0110895
DICPCG: Solving for p, Initial residual = 0.514503, Final residual = 0.0083699, No Iterations 1001
time step continuity errors : sum local = 0.0159632, global = -0.000707128, cumulative = -0.0117966
DILUPBiCG: Solving for epsilon, Initial residual = 0.976504, Final residual = 2.92807e-06, No Iterations 35
DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 5.42478e-06, No Iterations 22
bounding k, min: -2.33761e+06 max: 284635 average: -0.179143
ExecutionTime = 282.47 s ClockTime = 284 s

Time = 0.002

Courant Number mean: 0.855099 max: 1116.44
DILUPBiCG: Solving for Ux, Initial residual = 0.998287, Final residual = 9.48058e-06, No Iterations 7
DILUPBiCG: Solving for Uy, Initial residual = 0.684376, Final residual = 5.72911e-06, No Iterations 4
DILUPBiCG: Solving for Uz, Initial residual = 0.791918, Final residual = 4.9379e-06, No Iterations 4
DILUPBiCG: Solving for T, Initial residual = 0.966604, Final residual = 4.81849e-06, No Iterations 6
DICPCG: Solving for p, Initial residual = 0.937421, Final residual = 0.0905879, No Iterations 565
time step continuity errors : sum local = 0.187933, global = 0.0077102, cumulative = -0.00408645
DICPCG: Solving for p, Initial residual = 0.822426, Final residual = 0.000737089, No Iterations 1001
time step continuity errors : sum local = 0.0550033, global = 0.000874728, cumulative = -0.00321172
DILUPBiCG: Solving for epsilon, Initial residual = 0.708962, Final residual = 2.68383e-07, No Iterations 4
bounding epsilon, min: 1.29506e-20 max: 2.03704e+15 average: 1.83e+09
DILUPBiCG: Solving for k, Initial residual = 0.992225, Final residual = 1.14344e-06, No Iterations 3
bounding k, min: -5468.42 max: 6.78721e+07 average: 130.586
ExecutionTime = 635.98 s ClockTime = 638 s

Time = 0.003

Courant Number mean: 10.0358 max: 2.38499e+06
DILUPBiCG: Solving for Ux, Initial residual = 0.766492, Final residual = 1.19267e-13, No Iterations 4
DILUPBiCG: Solving for Uy, Initial residual = 0.749997, Final residual = 3.606e-06, No Iterations 3
DILUPBiCG: Solving for Uz, Initial residual = 0.236285, Final residual = 3.5269e-13, No Iterations 4
DILUPBiCG: Solving for T, Initial residual = 0.978144, Final residual = 5.08548e-15, No Iterations 4
DICPCG: Solving for p, Initial residual = 0.997824, Final residual = 0.0959205, No Iterations 1
time step continuity errors : sum local = 24570.4, global = 967.88, cumulative = 967.877
DICPCG: Solving for p, Initial residual = 0.0464776, Final residual = 1.53167e-05, No Iterations 1001
time step continuity errors : sum local = 1.78669e+10, global = 2.35003e+09, cumulative = 2.35003e+09
DILUPBiCG: Solving for epsilon, Initial residual = 1, Final residual = 9.60249e-06, No Iterations 404
bounding epsilon, min: -1.19737e+29 max: 5.35913e+37 average: 3.07046e+31
DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 6.38833e-07, No Iterations 7
bounding k, min: -2.24279e+19 max: 7.52278e+22 average: 1.09231e+17
ExecutionTime = 1040.99 s ClockTime = 1043 s

Time = 0.004

Courant Number mean: 1.92082e+13 max: 9.199e+18
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib/libc.so.6"
#3 Foam:ILUPreconditioner::calcReciprocalD(Foam::Fi eld<double>&, Foam::lduMatrix const&) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#4 Foam:ILUPreconditioner:ILUPreconditioner(Foam: :lduMatrix::solver const&, Foam::dictionary const&) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#5 Foam::lduMatrix:reconditioner::addasymMatrixCons tructorToTable<Foam:ILUPreconditioner>::New(Foam ::lduMatrix::solver const&, Foam::dictionary const&) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#6 Foam::lduMatrix:reconditioner::New(Foam::lduMatr ix::solver const&, Foam::dictionary const&) in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#7 Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#8 Foam::fvMatrix<Foam::Vector<double> >::solve(Foam::dictionary const&) in "/opt/OpenFOAM/OpenFOAM-1.6/applications/bin/linux64GccDPOpt/buoyantBoussinesqPisoFoam"
#9 main in "/opt/OpenFOAM/OpenFOAM-1.6/applications/bin/linux64GccDPOpt/buoyantBoussinesqPisoFoam"
#10 __libc_start_main in "/lib/libc.so.6"
#11 _start at /usr/src/packages/BUILD/glibc-2.9/csu/../sysdeps/x86_64/elf/start.S:116
Gleitkomma-Ausnahme

I see, that my Co number is far to high, and that must be something with the BC conditions. But I don't know, what else I could try.
A guess would be, to change the value for p at the wall from uniform 0 to something else, but somehow, I don't expect, that this would solve the problem.

Best regards!

[vichty]

Actually I have tried the Tutorial as well and have some questions about the boundary conditions.
1. What does rhok mean? and why is uniform 0?

floor
{
type buoyantPressure;
rho rhok;
value uniform 0;
}

2. At the wall i do not wanna have zeroGradient or uniform, i wanna have that I can add a Gradient of the temprature.

Thanks

[scotth2o]

I've never run this example but something is wrong with you Pressure

DICPCG: Solving for p, Initial residual = 0.937421, Final residual = 0.0905879, No Iterations 565
time step continuity errors : sum local = 0.187933, global = 0.0077102, cumulative = -0.00408645
DICPCG: Solving for p, Initial residual = 0.822426, Final residual = 0.000737089, No Iterations 1001

1001 iterations is too many

[nscurtu]

Hi,

I have the same trouble like Erik!

I have solved a natural convection problem with boussinesqBuoyantFoam of OpenFoam 1.5.

Two weeks ago I have seen that the thermophysical module was modified in 1.6 and that the compressible buoyantFoam (1.5) gives wrong results but buoyantPisoFoam (1.6) is ok.
Now I am in doubt if the incompressible module buoyantBoussinesqPisoFoam (1.6) is similar to boussinesqBuoyantFoam (1.5).

Therefore I tried to transpose my natural convection problem to
buoyantBoussinesqPisoFoam.
There are some different insignificant inputs in the transportProperties
file and a significant modification of the pressure boundary condition.
Namely, if one can use zeroGradient for p at the wall in 1.5, in 1.6 one
have to set the buoyantPressure type.
I do that, and kept the input parameters in the new case for 1.6.
One cannot set "type buoyantPressure" in boussinesqBuoyantFoam (1.5), and "type zeroGradient" for pressure in buoyantBoussinesqPisoFoam (1.6) doese not work.
So, one cannot test a simulation case for comparison.

The main trouble with buoyantBoussinesqPisoFoam (1.6) is that the
pressure solver becomes unstable after a certain number of time steps.
First I have tried with constant time step and than with adjustable time
step but the result is the same. The Iterations of the pressure solver becomes larger reaching the value 1001 and then the run is blowing up.

regards