setRDeltaT.H

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011-2015 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
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    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
\*---------------------------------------------------------------------------*/
 
{
    volScalarField& rDeltaT = trDeltaT();
 
    const dictionary& pimpleDict = pimple.dict();
 
    // Maximum flow Courant number
    scalar maxCo(readScalar(pimpleDict.lookup("maxCo")));
 
    // Maximum time scale
    scalar maxDeltaT(pimpleDict.lookupOrDefault<scalar>("maxDeltaT", GREAT));
 
    // Smoothing parameter (0-1) when smoothing iterations > 0
    scalar rDeltaTSmoothingCoeff
    (
        pimpleDict.lookupOrDefault<scalar>("rDeltaTSmoothingCoeff", 0.1)
    );
 
    // Damping coefficient (1-0)
    scalar rDeltaTDampingCoeff
    (
        pimpleDict.lookupOrDefault<scalar>("rDeltaTDampingCoeff", 0.2)
    );
 
    // Maximum change in cell temperature per iteration
    // (relative to previous value)
    scalar alphaTemp(pimpleDict.lookupOrDefault("alphaTemp", 0.05));
 
 
    Info<< "Time scales min/max:" << endl;
 
    // Cache old reciprocal time scale field
    volScalarField rDeltaT0("rDeltaT0", rDeltaT);
 
    // Flow time scale
    {
        rDeltaT.dimensionedInternalField() =
        (
            fvc::surfaceSum(mag(phi))().dimensionedInternalField()
           /((2*maxCo)*mesh.V()*rho.dimensionedInternalField())
        );
 
        // Limit the largest time scale
        rDeltaT.max(1/maxDeltaT);
 
        Info<< "    Flow        = "
            << gMin(1/rDeltaT.internalField()) << ", "
            << gMax(1/rDeltaT.internalField()) << endl;
    }
 
    // Reaction source time scale
    {
        volScalarField::DimensionedInternalField rDeltaTT
        (
            mag
            (
               parcels.hsTrans()/(mesh.V()*runTime.deltaT())
             + combustion->Sh()()
            )
           /(
               alphaTemp
              *rho.dimensionedInternalField()
              *thermo.Cp()().dimensionedInternalField()
              *T.dimensionedInternalField()
           )
        );
 
        Info<< "    Temperature = "
            << gMin(1/(rDeltaTT.field() + VSMALL)) << ", "
            << gMax(1/(rDeltaTT.field() + VSMALL)) << endl;
 
        rDeltaT.dimensionedInternalField() = max
        (
            rDeltaT.dimensionedInternalField(),
            rDeltaTT
        );
    }
 
    // Update tho boundary values of the reciprocal time-step
    rDeltaT.correctBoundaryConditions();
 
    // Spatially smooth the time scale field
    if (rDeltaTSmoothingCoeff < 1.0)
    {
        fvc::smooth(rDeltaT, rDeltaTSmoothingCoeff);
    }
 
    // Limit rate of change of time scale
    // - reduce as much as required
    // - only increase at a fraction of old time scale
    if
    (
        rDeltaTDampingCoeff < 1.0
     && runTime.timeIndex() > runTime.startTimeIndex() + 1
    )
    {
        rDeltaT = max
        (
            rDeltaT,
            (scalar(1.0) - rDeltaTDampingCoeff)*rDeltaT0
        );
    }
 
    Info<< "    Overall     = "
        << gMin(1/rDeltaT.internalField())
        << ", " << gMax(1/rDeltaT.internalField()) << endl;
}
 
 
// ************************************************************************* //