# OverPimpleDyMFoam

OverPimpleDyMFoam

Transient solver for incompressible flow of Newtonian fluids on a moving mesh using the PIMPLE (merged PISO-SIMPLE) algorithm. Turbulence modelling is generic, i.e. laminar, RAS or LES may be selected.

## Solution Strategy

The solver follows a segregated solution strategy. This means that the equations for each variable characterizing the system (the velocity $\bold u$, the pressure $p$ and the variables characterizing turbulence) is solved sequentially and the solution of the preceding equations is inserted in the subsequent equation. The non-linearity appearing in the momentum equation (the face flux $\phi_f$ which is a function of the velocity) is resolved by computing it from the velocity and pressure values of the preceding iteration. The dependence from the pressure is introduced to avoid a decoupling between the momentum and pressure equations and hence the appearance of high frequency oscillation in the solution (check board effect). The first equation to be solve is the momentum equation. It delivers a velocity field $\bold u^*$ which is in general not divergence free, i.e. it does not satisfy the continuity equation. After that the momentum and the continuity equations are used to construct an equation for the pressure. The aim is to obtain a pressure field $p^{n}$, which, if inserted in the momentum equation, delivers a divergence free velocity field $\bold u$. After correcting the velocity field, the equations for turbulence are solved. The above iterative solution procedure is repeated until convergence.

The overset method allows to solve the governing equaiton on a set of disjoint meshes, i.e., the meshes are not connected over faces. The coupling between the differnt meshes is done over an implicit interpolation.

The source code can be found in overPimpleDyMFoam.C



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Application
overPimpleDyMFoam

Group
grpIncompressibleSolvers grpMovingMeshSolvers

Description
Transient solver for incompressible flow of Newtonian fluids
on a moving mesh using the PIMPLE (merged PISO-SIMPLE) algorithm.

Turbulence modelling is generic, i.e. laminar, RAS or LES may be selected.

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

#include "fvCFD.H"
#include "dynamicFvMesh.H"
#include "singlePhaseTransportModel.H"
#include "turbulentTransportModel.H"
#include "pimpleControl.H"
#include "fvOptions.H"

#include "cellCellStencilObject.H"
#include "localMin.H"
#include "interpolationCellPoint.H"
#include "transform.H"
#include "fvMeshSubset.H"

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

int main(int argc, char *argv[])
{
(
"Transient solver for incompressible, turbulent flow"
" on a moving mesh."
);

#include "postProcess.H"

#include "setRootCaseLists.H"
#include "createTime.H"
#include "createDynamicFvMesh.H"
#include "initContinuityErrs.H"

pimpleControl pimple(mesh);

#include "createFields.H"
#include "createUf.H"
#include "createMRF.H"
#include "createFvOptions.H"
#include "createControls.H"
#include "CourantNo.H"
#include "setInitialDeltaT.H"

turbulence->validate();

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

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

while (runTime.run())
{
#include "CourantNo.H"

#include "setDeltaT.H"

++runTime;

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

bool changed = mesh.update();

if (changed)
{
#include "setInterpolatedCells.H"

(
);

// Zero Uf on old faceMask (H-I)
// Update Uf and phi on new C-I faces
phi = mesh.Sf() & Uf;

// Zero phi on current H-I
(
);
}

if (mesh.changing() && correctPhi)
{
// Calculate absolute flux from the mapped surface velocity
#include "correctPhi.H"
}

// Make the flux relative to the mesh motion
fvc::makeRelative(phi, U);

if (mesh.changing() && checkMeshCourantNo)
{
#include "meshCourantNo.H"
}

// --- Pressure-velocity PIMPLE corrector loop
while (pimple.loop())
{
#include "UEqn.H"

// --- Pressure corrector loop
while (pimple.correct())
{
#include "pEqn.H"
}

if (pimple.turbCorr())
{
laminarTransport.correct();
turbulence->correct();
}
}

runTime.write();

runTime.printExecutionTime(Info);
}

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

return 0;
}

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