[dennymathewalex]

Hello Everyone 😊,
I am Denny and I am new to OpenFoam. I am learning OpenFoam by simulating a flow inside a rectangular chamber with simpleFoam solver. The boundaries are shown in the figures (inlet-Green, outlet-Red, wall-Blue). The geometry was created using Salome and mesh was generated using snappyHexMesh (only castellated Mesh part is True). Using the checkMesh, the quality of the mesh is OK. I ran the simulation to 2000 and 6000 time steps with delta t of 1 but could not achieve convergence. I have attached the velocity plot for time steps 1802 and 1902.
I have pasted the boundary condition U and p, controlDict, fvSchemes, fvSolution below.
What are the steps to be taken to get a good convergence in this case?
Thank you for your help 😊.
-------------------- U --------------------------------
internalField uniform (0 0 0);

boundaryField
{
inlet
{
type fixedValue;
value uniform (1 0 0);
}

outlet
{
type zeroGradient;
value uniform (0 0 0);
}

wall
{
type noSlip;
value uniform (0 0 0);
}

}


---------------- p ----------------------------
internalField uniform 0;

boundaryField
{
inlet
{
type zeroGradient;
}

outlet
{
type fixedValue;
value uniform 0;
}

wall
{
type zeroGradient;
}

}

--------------------- controlDict ------------------------

application simpleFoam;

startFrom startTime;

startTime 1;

stopAt endTime;

endTime 6000;

deltaT 1;

writeControl timeStep;

writeInterval 100;

purgeWrite 0;

writeFormat ascii;

writePrecision 6;

writeCompression off;

timeFormat general;

timePrecision 6;

runTimeModifiable true;

--------------- fvSchemes ---------------------
ddtSchemes
{
default steadyState;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
default none;
div(phi,U) bounded Gauss upwind;
div((nuEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}

------------------- fvSolution ---------------------
solvers
{
p
{
solver GAMG;
tolerance 1e-06;
relTol 0.1;
smoother GaussSeidel;
}

U
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-05;
relTol 0.1;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 0;
nCorrectors 3;
consistent yes;

residualControl
{
p 1e-2;
U 1e-3;
}
}

relaxationFactors
{
fields
{
p 1;
}
equations
{
U 0.9; // 0.9 is more stable but 0.95 more convergent
}
}