setDeltaT.H

/*---------------------------------------------------------------------------*\
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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
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    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
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    Copyright (C) 2017 OpenCFD Ltd.
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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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Global
    setDeltaT

Description
    Reset the timestep to maintain a constant maximum courant Number.
    Reduction of time-step is immediate, but increase is damped to avoid
    unstable oscillations.

\*---------------------------------------------------------------------------*/

if (adjustTimeStep)
{
    scalar maxDeltaTFact =
        min
        (
            maxCo/(CoNum + SMALL),
            min
            (
                maxAlphaCo/(alphaCoNum + SMALL),
                min
                (
                    maxAlphaDdt/(ddtAlphaNum + SMALL),
                    maxDi/(DiNum + SMALL)
                )
            )
        );

    scalar deltaTFact = min(min(maxDeltaTFact, 1.0 + 0.1*maxDeltaTFact), 1.2);

    runTime.setDeltaT
    (
        min
        (
            deltaTFact*runTime.deltaTValue(),
            maxDeltaT
        )
    );
    Info<< "deltaT = " <<  runTime.deltaTValue() << endl;
}


// ************************************************************************* //