/*---------------------------------------------------------------------------*\
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-------------------------------------------------------------------------------
    Copyright (C) 2011-2016 OpenFOAM Foundation
    Copyright (C) 2019 OpenCFD Ltd.
-------------------------------------------------------------------------------
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.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    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/>.

Application
    icoFoam

Group
    grpIncompressibleSolvers

Description
    Transient solver for incompressible, laminar flow of Newtonian fluids.

    \heading Solver details
    The solver uses the PISO algorithm to solve the continuity equation:

        \f[
            \div \vec{U} = 0
        \f]

    and momentum equation:

        \f[
            \ddt{\vec{U}}
          + \div \left( \vec{U} \vec{U} \right)
          - \div \left(\nu \grad \vec{U} \right)
          = - \grad p
        \f]

    Where:
    \vartable
        \vec{U} | Velocity
        p       | Pressure
    \endvartable

    \heading Required fields
    \plaintable
        U       | Velocity [m/s]
        p       | Kinematic pressure, p/rho [m2/s2]
    \endplaintable

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

#include "gpufvCFD.H"
#include "pisoControl.H"
#include <sys/time.h>

struct my_timer
{
    struct timeval start_time, end_time;
    double time_use;

    void start()
    {
        gettimeofday(&start_time, NULL);
    }

    void stop()
    {
        gettimeofday(&end_time, NULL);
        time_use = (end_time.tv_sec - start_time.tv_sec) + (double)(end_time.tv_usec - start_time.tv_usec)/1000000.0;
    }
};

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

int main(int argc, char *argv[])
{

my_timer tm;
tm.start();

    argList::addNote
    (
        "Transient solver for incompressible, laminar flow"
        " of Newtonian fluids."
    );

    #include "gpupostProcess.H"

    #include "addCheckCaseOptions.H"
    #include "setRootCaseLists.H"
    #include "createTime.H"
    #include "gpucreateMesh.H"

    pisoControl piso(mesh);

    #include "createFields.H"
    #include "initContinuityErrs.H"

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

    Info<< "\nStarting time loop\n" << endl;

    while (runTime.loop())
    {
        Info<< "Time = " << runTime.timeName() << nl << endl;

my_timer tm1;
tm1.start();

        #include "gpuCourantNo.H"

        // Momentum predictor

        gpufvVectorMatrix UEqn
        (
            fvm::ddt(U)
          + fvm::div(phi, U)
          - fvm::laplacian(nu, U)
        );

        if (piso.momentumPredictor())
        {
            solve(UEqn == -fvc::grad(p));
        }

        // --- PISO loop
        while (piso.correct())
        {
            volScalargpuField rAU(1.0/UEqn.A());
            volVectorgpuField HbyA(constrainHbyA(rAU*UEqn.H(), U, p));
            surfaceScalargpuField phiHbyA
            (
                "phiHbyA",
                fvc::flux(HbyA)
              + fvc::interpolate(rAU)*fvc::ddtCorr(U, phi)
            );

            adjustPhi(phiHbyA, U, p);

            // Update the pressure BCs to ensure flux consistency
            constrainPressure(p, U, phiHbyA, rAU);

            // Non-orthogonal pressure corrector loop
            while (piso.correctNonOrthogonal())
            {
                // Pressure corrector

                gpufvScalarMatrix pEqn
                (
                    fvm::laplacian(rAU, p) == fvc::div(phiHbyA)
                );

                pEqn.setReference(pRefCell, pRefValue);

                pEqn.solve(mesh.solver(p.select(piso.finalInnerIter())));

                if (piso.finalNonOrthogonalIter())
                {
                    phi = phiHbyA - pEqn.flux();
                }
            }

            #include "gpucontinuityErrs.H"

            U = HbyA - rAU*fvc::grad(p);
            U.correctBoundaryConditions();
        }

        runTime.write();

        runTime.printExecutionTime(Info);

tm1.stop();
Info<<"------Time Step = "<<tm1.time_use<<"s-------------------"<<endl;
    }

tm.stop();
Info<<"------all the time = "<<tm.time_use<< " s--------------------"<<endl;

    Info<< "End\n" << endl;

    return 0;
}


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