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reactingFoam::setRDeltaT: Add support for limiting the local time-step by the reaction rates

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e.g. in the reactingFoam/laminar/counterFlowFlame2DLTS tutorial:

PIMPLE
{
    momentumPredictor no;
    nOuterCorrectors  1;
    nCorrectors     1;
    nNonOrthogonalCorrectors 0;

    maxDeltaT       1e-2;
    maxCo           1;
    alphaTemp       0.05;
    alphaY          0.05;
    Yref
    {
        O2          0.1;
        ".*"        1;
    }
    rDeltaTSmoothingCoeff 1;
    rDeltaTDampingCoeff 1;
}

will limit the LTS time-step according to the rate of consumption of 'O2'
normalized by the reference mass-fraction of 0.1 and all other species
normalized by the reference mass-fraction of 1.  Additionally the time-step
factor of 'alphaY' is applied to all species.  Only the species specified in the
'Yref' sub-dictionary are included in the LTS limiter and if 'alphaY' is omitted
or set to 1 the reaction rates are not included in the LTS limiter.
This commit is contained in:
Henry Weller
2016-12-19 14:19:31 +00:00
parent 0087bb8027
commit 6cae0fdacb
1 changed files with 72 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

86
applications/solvers/combustion/reactingFoam/setRDeltaT.H
View File

@ -43,13 +43,16 @@ License
// Damping coefficient (1-0)
scalar rDeltaTDampingCoeff
(
pimpleDict.lookupOrDefault<scalar>("rDeltaTDampingCoeff", 1)
pimpleDict.lookupOrDefault<scalar>("rDeltaTDampingCoeff", 1.0)
);
// Maximum change in cell temperature per iteration
// (relative to previous value)
scalar alphaTemp(pimpleDict.lookupOrDefault("alphaTemp", 0.05));
// Maximum change in cell concentration per iteration
// (relative to reference value)
scalar alphaY(pimpleDict.lookupOrDefault("alphaY", 1.0));
Info<< "Time scales min/max:" << endl;
@ -68,12 +71,12 @@ License
rDeltaT.max(1/maxDeltaT);
Info<< " Flow = "
<< gMin(1/rDeltaT.primitiveField()) << ", "
<< gMax(1/rDeltaT.primitiveField()) << endl;
<< 1/gMax(rDeltaT.primitiveField()) << ", "
<< 1/gMin(rDeltaT.primitiveField()) << endl;
}
// Reaction source time scale
if (alphaTemp < 1.0)
// Heat release rate time scale
if (alphaTemp < 1)
{
volScalarField::Internal rDeltaTT
(
@ -81,21 +84,76 @@ License
);
Info<< " Temperature = "
<< gMin(1/(rDeltaTT.field() + VSMALL)) << ", "
<< gMax(1/(rDeltaTT.field() + VSMALL)) << endl;
<< 1/(gMax(rDeltaTT.field()) + VSMALL) << ", "
<< 1/(gMin(rDeltaTT.field()) + VSMALL) << endl;
rDeltaT.ref() = max
rDeltaT.ref() = max(rDeltaT(), rDeltaTT);
}
// Reaction rate time scale
if (alphaY < 1)
{
dictionary Yref(pimpleDict.subDict("Yref"));
volScalarField::Internal rDeltaTY
(
rDeltaT(),
rDeltaTT
IOobject
(
"rDeltaTY",
runTime.timeName(),
mesh
),
mesh,
dimensionedScalar("rDeltaTY", rDeltaT.dimensions(), 0)
);
bool foundY = false;
forAll(Y, i)
{
if (i != inertIndex && composition.active(i))
{
volScalarField& Yi = Y[i];
if (Yref.found(Yi.name()))
{
foundY = true;
scalar Yrefi = readScalar(Yref.lookup(Yi.name()));
rDeltaTY.field() = max
(
mag
(
reaction->R(Yi)().source()
/((Yrefi*alphaY)*(rho*mesh.V()))
),
rDeltaTY
);
}
}
}
if (foundY)
{
Info<< " Composition = "
<< 1/(gMax(rDeltaTY.field()) + VSMALL) << ", "
<< 1/(gMin(rDeltaTY.field()) + VSMALL) << endl;
rDeltaT.ref() = max(rDeltaT(), rDeltaTY);
}
else
{
IOWarningIn(args.executable().c_str(), Yref)
<< "Cannot find any active species in Yref " << Yref
<< endl;
}
}
// Update tho boundary values of the reciprocal time-step
rDeltaT.correctBoundaryConditions();
// Spatially smooth the time scale field
if (rDeltaTSmoothingCoeff < 1.0)
if (rDeltaTSmoothingCoeff < 1)
{
fvc::smooth(rDeltaT, rDeltaTSmoothingCoeff);
}
@ -105,7 +163,7 @@ License
// - only increase at a fraction of old time scale
if
(
rDeltaTDampingCoeff < 1.0
rDeltaTDampingCoeff < 1
&& runTime.timeIndex() > runTime.startTimeIndex() + 1
)
{
@ -120,8 +178,8 @@ License
rDeltaT.correctBoundaryConditions();
Info<< " Overall = "
<< gMin(1/rDeltaT.primitiveField())
<< ", " << gMax(1/rDeltaT.primitiveField()) << endl;
<< 1/gMax(rDeltaT.primitiveField())
<< ", " << 1/gMin(rDeltaT.primitiveField()) << endl;
}