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    Copyright (C) 2019 OpenCFD Ltd.
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Global
    meanMomentumEnergyAndNMols.H

Description
    Calculates and prints the mean momentum and energy in the system
    and the number of molecules.

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


vector singleStepTotalLinearMomentum(Zero);

vector singleStepTotalAngularMomentum(Zero);

scalar singleStepMaxVelocityMag = 0.0;

scalar singleStepTotalMass = 0.0;

scalar singleStepTotalLinearKE = 0.0;

scalar singleStepTotalAngularKE = 0.0;

scalar singleStepTotalPE = 0.0;

scalar singleStepTotalrDotf = 0.0;

//vector singleStepCentreOfMass(Zero);

label singleStepNMols = molecules.size();

label singleStepDOFs = 0;

{
    for (const molecule& mol : molecules)
    {
        const label molId = mol.id();

        scalar molMass(molecules.constProps(molId).mass());

        singleStepTotalMass += molMass;

        //singleStepCentreOfMass += mol.position()*molMass;
    }

    // if (singleStepNMols)
    // {
    //     singleStepCentreOfMass /= singleStepTotalMass;
    // }

    for (const molecule& mol : molecules)
    {
        const label molId = mol.id();

        const molecule::constantProperties cP(molecules.constProps(molId));

        scalar molMass(cP.mass());

        const diagTensor& molMoI(cP.momentOfInertia());

        const vector& molV(mol.v());

        const vector molOmega(inv(molMoI) & mol.pi());

        vector molPiGlobal = mol.Q() & mol.pi();

        singleStepTotalLinearMomentum += molV * molMass;

        singleStepTotalAngularMomentum += molPiGlobal;
        //+((mol.position() - singleStepCentreOfMass) ^ (molV * molMass));

        if (mag(molV) > singleStepMaxVelocityMag)
        {
            singleStepMaxVelocityMag = mag(molV);
        }

        singleStepTotalLinearKE += 0.5*molMass*magSqr(molV);

        singleStepTotalAngularKE += 0.5*(molOmega & molMoI & molOmega);

        singleStepTotalPE += mol.potentialEnergy();

        singleStepTotalrDotf += tr(mol.rf());

        singleStepDOFs += cP.degreesOfFreedom();
    }
}

if (Pstream::parRun())
{
    reduce(singleStepTotalLinearMomentum, sumOp<vector>());

    reduce(singleStepTotalAngularMomentum, sumOp<vector>());

    reduce(singleStepMaxVelocityMag, maxOp<scalar>());

    reduce(singleStepTotalMass, sumOp<scalar>());

    reduce(singleStepTotalLinearKE, sumOp<scalar>());

    reduce(singleStepTotalAngularKE, sumOp<scalar>());

    reduce(singleStepTotalPE, sumOp<scalar>());

    reduce(singleStepTotalrDotf, sumOp<scalar>());

    reduce(singleStepNMols, sumOp<label>());

    reduce(singleStepDOFs, sumOp<label>());
}

if (singleStepNMols)
{
    Info<< "Number of molecules in system = "
        << singleStepNMols << nl
        << "Overall number density = "
        << singleStepNMols/meshVolume << nl
        << "Overall mass density = "
        << singleStepTotalMass/meshVolume << nl
        << "Average linear momentum per molecule = "
        << singleStepTotalLinearMomentum/singleStepNMols << ' '
        << mag(singleStepTotalLinearMomentum)/singleStepNMols << nl
        << "Average angular momentum per molecule = "
        << singleStepTotalAngularMomentum << ' '
        << mag(singleStepTotalAngularMomentum)/singleStepNMols << nl
        << "Maximum |velocity| = "
        << singleStepMaxVelocityMag << nl
        << "Average linear KE per molecule = "
        << singleStepTotalLinearKE/singleStepNMols << nl
        << "Average angular KE per molecule = "
        << singleStepTotalAngularKE/singleStepNMols << nl
        << "Average PE per molecule = "
        << singleStepTotalPE/singleStepNMols << nl
        << "Average TE per molecule = "
        <<
        (
            singleStepTotalLinearKE
          + singleStepTotalAngularKE
          + singleStepTotalPE
        )
        /singleStepNMols
        << endl;

        // Info<< singleStepNMols << " "
        //     << singleStepTotalMomentum/singleStepTotalMass << " "
        //     << singleStepMaxVelocityMag << " "
        //     << singleStepTotalKE/singleStepNMols << " "
        //     << singleStepTotalPE/singleStepNMols << " "
        //     << (singleStepTotalKE + singleStepTotalPE)
        //        /singleStepNMols << endl;
}
else
{
    Info<< "No molecules in system" << endl;
}


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