Hi, FOAMers,
I'm trying to simulate transient two-gases flow in a chamber that features Gas1 flowing from a cylindrical shape inlet and mixing with Gas2, the mixture later is discharged from 10 outlets. I hope to check the internal pressure and velocity distribution as well as the density variation. The flow is supposed to be very slow, so I used laminar model. The iteration seems running OK, but with very weird volume fraction value which keeps very low, even negative initially. I tried many times, but have not solved it yet. The U, p, controlDict, fvSolution, and the iteration logs are as follows, any comments are much appreciated!
- U:
dimensions [0 1 -1 0 0 0 0];
internalField uniform (0 0 0);
boundaryField
{
inlet
{
type cylindricalInletVelocity;
axis (0 0 1);
origin (0 0 0);
axialVelocity 0.5;
rpm 0;
radialVelocity 0.1;
value uniform (0 0 0);
}
outlet
{
type pressureInletOutletVelocity;
value uniform (0.1 0.1 0);
}
wall
{
type noSlip;
}
}
- p_rgh:
dimensions [1 -1 -2 0 0 0 0];
internalField uniform 0;
boundaryField
{
inlet
{
type fixedFluxPressure;
value uniform 0;
}
outlet
{
type totalPressure;
p0 uniform 0;
U U;
value uniform 0;
phi phi;
rho rho;
psi none;
gamma 0;
}
wall
{
type fixedFluxPressure;
value uniform 0;
}
}
- controlDict:
application interFoam;
startFrom startTime;
startTime 0;
stopAt endTime;
endTime 10.0;
deltaT 0.001;
writeControl adjustableRunTime;
writeInterval 0.5;
purgeWrite 0;
writeFormat ascii;
writePrecision 5;
writeCompression compressed;
timeFormat general;
timePrecision 6;
graphFormat raw;
runTimeModifiable yes;
adjustTimeStep yes;
maxCo 1;
maxAlphaCo 0.5;
maxDeltaT 0.02;
- fvSolution:
PIMPLE
{
momentumPredictor no;
nCorrectors 2;
nOuterCorrectors 1;
nNonOrthogonalCorrectors 2;
nAlphaCorr 1;
nAlphaSubCycles 3;
cAlpha 1.5;
correctPhi yes;
pRefCell 0;
pRefValue 0;
residualControl
{
U
{
relTol 0;
tolerance 1.0E-5;
}
p_rgh
{
relTol 0;
tolerance 1.0E-5;
}
"alpha.*"
{
relTol 0;
tolerance 1.0E-5;
}
}
}
solvers
{
"pcorr.*"
{
solver PCG;
preconditioner
{
preconditioner GAMG;
tolerance 1e-5;
relTol 0;
smoother DICGaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
nFinestSweeps 2;
cacheAgglomeration false;
nCellsInCoarsestLevel 10;
agglomerator faceAreaPair;
mergeLevels 1;
}
tolerance 1e-05;
relTol 0;
maxIter 100;
minIter 1;
}
"alpha.air.*"
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-6;
relTol 0;
nSweeps 1;
minIter 1;
nAlphaCorr 1;
nAlphaSubCycles 3;
cAlpha 1.5;
}
p_rgh
{
solver GAMG;
agglomerator faceAreaPair;
mergeLevels 1;
cacheAgglomeration true;
nCellsInCoarsestLevel 200;
tolerance 1e-10;
relTol 0.01;
smoother GaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
nFinestSweeps 2;
minIter 1;
}
p_rghFinal
{
$p_rgh;
relTol 0;
}
U
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-6;
relTol 0.1;
minIter 1;
}
relaxationFactors
{
equations
{
".*" 1;
}
}
}
- iteration logs:
PIMPLE: iteration 1
MULES: Solving for alpha.air
Phase-1 volume fraction = -1.0624e-07 Min(alpha.air) = -0.0037495 Max(alpha.air) = 1
MULES: Solving for alpha.air
Phase-1 volume fraction = -1.0624e-07 Min(alpha.air) = -0.0037495 Max(alpha.air) = 1
MULES: Solving for alpha.air
Phase-1 volume fraction = -1.0624e-07 Min(alpha.air) = -0.0037495 Max(alpha.air) = 1
GAMG: Solving for p_rgh, Initial residual = 0.98828, Final residual = 0.0093862, No Iterations 3
GAMG: Solving for p_rgh, Initial residual = 0.91015, Final residual = 0.0075157, No Iterations 4
GAMG: Solving for p_rgh, Initial residual = 0.94942, Final residual = 0.0081391, No Iterations 4
time step continuity errors : sum local = 5.9038e-10, global = -1.1537e-13, cumulative = 3.4232e-10
GAMG: Solving for p_rgh, Initial residual = 0.9554, Final residual = 0.0078791, No Iterations 4
GAMG: Solving for p_rgh, Initial residual = 0.96615, Final residual = 0.0083069, No Iterations 4
GAMG: Solving for p_rgh, Initial residual = 0.96422, Final residual = 8.9279e-11, No Iterations 33
time step continuity errors : sum local = 4.8867e-17, global = 1.0964e-17, cumulative = 3.4232e-10
ExecutionTime = 2452.4 s ClockTime = 2456 s
Courant Number mean: 1.2276e-07 max: 7.7371
Interface Courant Number mean: 0 max: 0
deltaT = 7.577e-104
Time = 0.00289982
PIMPLE: iteration 1
MULES: Solving for alpha.air
Phase-1 volume fraction = -1.0624e-07 Min(alpha.air) = -0.0037495 Max(alpha.air) = 1
MULES: Solving for alpha.air
Phase-1 volume fraction = -1.0624e-07 Min(alpha.air) = -0.0037495 Max(alpha.air) = 1
MULES: Solving for alpha.air
Phase-1 volume fraction = -1.0624e-07 Min(alpha.air) = -0.0037495 Max(alpha.air) = 1
GAMG: Solving for p_rgh, Initial residual = 0.98827, Final residual = 0.0093915, No Iterations 3
GAMG: Solving for p_rgh, Initial residual = 0.91004, Final residual = 0.0075233, No Iterations 4
GAMG: Solving for p_rgh, Initial residual = 0.94936, Final residual = 0.0081475, No Iterations 4
time step continuity errors : sum local = 5.9019e-10, global = -1.1572e-13, cumulative = 3.4221e-10
GAMG: Solving for p_rgh, Initial residual = 0.95534, Final residual = 0.0078871, No Iterations 4
GAMG: Solving for p_rgh, Initial residual = 0.9661, Final residual = 0.0083156, No Iterations 4
GAMG: Solving for p_rgh, Initial residual = 0.96417, Final residual = 9.0896e-11, No Iterations 33
time step continuity errors : sum local = 4.9684e-17, global = 1.1107e-17, cumulative = 3.4221e-10
ExecutionTime = 2472.9 s ClockTime = 2477 s
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