[CFD_user_2012]

Dear all

I am running a simulation of the air flow in a room using buoyant simple foam.

I run the program and get the following error message

Not sure whats wrong

Please help

CFD_user


Create time

Create mesh for time = 0


Reading g
Reading thermophysical properties

Selecting thermodynamics package hPsiThermo<pureMixture<constTransport<specieThermo <hConstThermo<perfectGas>>>>>
Reading field U

Reading/calculating face flux field phi

Creating turbulence model

Selecting RAS turbulence model kEpsilon
kEpsilonCoeffs
{
Cmu 0.09;
C1 1.44;
C2 1.92;
C3 -0.33;
sigmak 1;
sigmaEps 1.3;
Prt 1;
}

Calculating field g.h

Reading field p_rgh


SIMPLE: convergence criteria
field p_rgh tolerance 0.01
field U tolerance 0.001
field h tolerance 0.001
field "(k|epsilon|omega)" tolerance 0.001


Starting time loop

Time = 1

DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 0.00488841, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 0.000946431, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 0.00347572, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 1, Final residual = 0.00107994, No Iterations 1
DICPCG: Solving for p_rgh, Initial residual = 0.653293, Final residual = 0.00648429, No Iterations 82
time step continuity errors : sum local = 0.658898, global = -4.7659e-17, cumulative = -4.7659e-17
rho max/min : 1.70542 0.61239
DILUPBiCG: Solving for epsilon, Initial residual = 0.99778, Final residual = 0.0385943, No Iterations 1
DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 0.022947, No Iterations 1
ExecutionTime = 11.81 s ClockTime = 12 s

Time = 2

DILUPBiCG: Solving for Ux, Initial residual = 0.132736, Final residual = 0.00281505, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.0335339, Final residual = 0.000215383, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.100024, Final residual = 0.00168842, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 1, Final residual = 0.00449013, No Iterations 1
DICPCG: Solving for p_rgh, Initial residual = 0.999999, Final residual = 0.859615, No Iterations 1001
time step continuity errors : sum local = 8.87527, global = 5.38735e-17, cumulative = 6.21446e-18
rho max/min : 362356 -1.21341e+06
DILUPBiCG: Solving for epsilon, Initial residual = 0.957201, Final residual = 0.00617101, No Iterations 2
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 log in "/lib/i386-linux-gnu/libm.so.6"
#4 Foam::compressible::RASModels::mutUWallFunctionFvP atchScalarField::calcYPlus(Foam::Field<double> const&) const in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libcompressibleRASModels.so"
#5 Foam::compressible::RASModels::mutUWallFunctionFvP atchScalarField::calcMut() const in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libcompressibleRASModels.so"
#6 Foam::compressible::RASModels::mutkWallFunctionFvP atchScalarField::updateCoeffs() in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libcompressibleRASModels.so"
#7 Foam::fvMatrix<double>::fvMatrix(Foam::GeometricFi eld<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::dimensionSet const&) in "/opt/openfoam210/platforms/linuxGccDPOpt/bin/buoyantSimpleFoam"
#8 Foam::tmp<Foam::fvMatrix<double> > Foam::fvm::Sp<double>(Foam:imensionedField<doubl e, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam210/platforms/linuxGccDPOpt/bin/buoyantSimpleFoam"
#9 Foam::compressible::RASModels::kEpsilon::correct() in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libcompressibleRASModels.so"
#10
in "/opt/openfoam210/platforms/linuxGccDPOpt/bin/buoyantSimpleFoam"
#11 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#12
in "/opt/openfoam210/platforms/linuxGccDPOpt/bin/buoyantSimpleFoam"
Floating point exception
openfoam@openfoam-VirtualBox:~/OpenFOAM/openfoam-2.1.0/run/tutorials/heatTransfer/buoyantSimpleFoam/hotRoom$

[MDeza]

I've got the same error. Did you ever figure out what was causing it?

[Tobi]

Hi,

do you have this error on your case or the tutorial case?

As you see the problem depend on the calculation of some equations:

DICPCG: Solving for p_rgh, Initial residual = 0.999999, Final residual = 0.859615, No Iterations 1001
time step continuity errors : sum local = 8.87527, global = 5.38735e-17, cumulative = 6.21446e-18
rho max/min : 362356 -1.21341e+06
DILUPBiCG: Solving for epsilon, Initial residual = 0.957201, Final residual = 0.00617101, No Iterations 2

In his case I think the pressure BC or volocity BC are not set correct. Therefor he got a blow up on p_rgh equation. Iterations of 1000 indicate a Problem with BC or Initial solution - especially in the first time steps. Additionally you see the residuals and the min/max values of rho.

I think a fluid never will get negativ density or 362356 kg/m³ - seems that he find a new - till now non found - fluid.

You should be able to solve your problem now.

Additionally:

Floating point exception

This error message give you a hint that you devide with Zero.

[calf.Z]

Originally Posted by Tobi

In his case I think the pressure BC or volocity BC are not set correct. Therefor he got a blow up on p_rgh equation. Iterations of 1000 indicate a Problem with BC or Initial solution - especially in the first time steps.

If I set GAMG for p_rgh, no iterations should below 100,but if I set PCG for p_rgh, it presents no iterations 1001. Does it indicate some problems with my BCs? Here are my set-ups：（I am using buoyantSimpleFoam）

p_rgh

boundaryField
{
    
    INLET
    {
        type            fixedFluxPressure;
        value           $internalField;
    }

    OUTLET
    {
        type            fixedValue;
        value           $internalField;
    }

    WALL
    {
        type            fixedFluxPressure;
        value           $internalField;
    }

}

U

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0.01 0);

boundaryField
{
    
    INLET
    {
        type            fixedValue;
        value           uniform (0 0.01 0);
    }

    OUTLET
    {
        type            pressureInletOutletVelocity;
        value           uniform (0 0.01 0);
    }

    WALL
    {
        type            noSlip;
    }

}

T

boundaryField
{
    
    INLET
    {
        type            fixedValue;
        value           $internalField;
    }

    OUTLET
    {
        type            inletOutlet;
        value           $internalField;
        inletValue      $internalField;
    }

    WALL
    {
        type            externalWallHeatFluxTemperature;
        mode            flux;
        q               uniform 6666;
        value           $internalField;
        kappaMethod     fluidThermo;
    }

}

Regards,
Calf.Z