[Gzy52597]

Hi Foamers,
I try to add gravity field in icoFoam to simulate natural cycle.

I added gravity term in UEqn and external heat source in TEqn.Then and run my code in the Square Cavity Flow.When I got the result，I found the mesh velocity for the upper and lower boundary regions is very large，but the mesh velocity of the inner area looks normal.The same is true for calculating only one step.
I can't understand where my problem is and how should I fix it. I'm guessing there might be a problem with the pressure correction.I will put my code and data at the end.For the convenience of calculation, I changed the unit of g Q rho.And The version I am using is OF9.

Thanks very much.
GZY

#include "fvCFD.H"
#include "pisoControl.H"

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

int main(int argc, char *argv[])
{
    #include "setRootCaseLists.H"
    #include "createTime.H"
    #include "createMesh.H"

    pisoControl piso(mesh);

    #include "createFields.H"
    #include "initContinuityErrs.H"
         
         int ixx;
	double   ttt[50000];
	double   r[50000];




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

    Info<< "\nStarting time loop\n" << endl;
    
    while (runTime.loop())
    {    
     
	ixx=0;
	forAll(T, cellI)
	{

	 ttt[ixx]=T[cellI];
         r[ixx]=11112.0-1.375*ttt[ixx];
         rho[cellI]=r[ixx];
         ixx++;
 	      
	}
	
	


	

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

        #include "CourantNo.H"

        // Momentum predictor
      
        fvVectorMatrix UEqn
        (
        
           fvm::ddt(rho,U)
          +rho*fvm::div(phi, U)
          -rho*fvm::laplacian(nu, U)
          -rho*g

        );


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

        // --- PISO loop
        while (piso.correct())
        {
            volScalarField rAU(1.0/UEqn.A());
            volVectorField HbyA(constrainHbyA(rAU*UEqn.H(), U, p));
            surfaceScalarField 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

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

                pEqn.setReference(pRefCell, pRefValue);

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

            #include "continuityErrs.H"

            U = HbyA - rAU*fvc::grad(p);
            U.correctBoundaryConditions();
           
        }
        
        
         
        fvScalarMatrix TEqn
        (
            fvm::ddt(T)
            + fvm::div(phi, T)
            - fvm::laplacian(DT, T)
            - Q
            
        );

        TEqn.solve();
        
        
        runTime.write();

        Info<< "ExecutionTime = " << runTime.elapsedCpuTime() << " s"
            << "  ClockTime = " << runTime.elapsedClockTime() << " s"
            << nl << endl;
            
	
	
    }
	
    Info<< "End\n" << endl;

    return 0;
}


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

/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  9
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    format      ascii;
    class       volVectorField;
    location    "0.005";
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

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(0.000149998 -0.0144296 0)
(0.000100535 -0.0144206 0)
(5.86655e-05 -0.0144149 0)
(1.99577e-05 -0.0144127 0)
(-1.85699e-05 -0.014412 0)
(-5.73086e-05 -0.0144113 0)
(-9.84487e-05 -0.0144123 0)
(-0.000147885 -0.0144192 0)
(-0.000205072 -0.0144354 0)
(-0.000302038 -0.0144533 0)
(-0.000447744 -0.0144797 0)
(-0.000711567 -0.014507 0)
(-0.000787918 -0.0141431 0)
(-0.000457033 -0.0115368 0)
)
;

boundaryField
{
    Wall
    {
        type            noSlip;
    }
    fixedWalls
    {
        type            noSlip;
    }
    frontAndBack
    {
        type            empty;
    }
}


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