setDeltaT.H

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/*---------------------------------------------------------------------------*\
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    Copyright (C) 2017 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.

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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 =
        Foam::min
        (
            maxCo/(CoNum + SMALL),
            Foam::min
            (
                maxAlphaCo/(alphaCoNum + SMALL),
                Foam::min
                (
                    maxAlphaDdt/(ddtAlphaNum + SMALL),
                    maxDi/(DiNum + SMALL)
                )
            )
        );

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

    runTime.setDeltaT
    (
        Foam::min
        (
            deltaTFact*runTime.deltaTValue(),
            maxDeltaT
        )
    );

    Info<< "deltaT = " <<  runTime.deltaTValue() << endl;
}


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