• Sub-dictionary SIMPLE in file fvSolution is important.
• nNonOrthogonalCorrectors is number of pressure equation steps (zero means one step)
• Parameters pMin, pMax, etc., are limits allowed for variables
• In sub-dictionary relaxationFactors there are under-relaxation factors for all variables.

fvSolution file for subsonic computations:

solvers
{
    p
    {
        solver          GAMG;
        tolerance       1e-8;
        relTol          0.001;
        smoother        GaussSeidel;
        cacheAgglomeration true;
        nCellsInCoarsestLevel 20;
        agglomerator    faceAreaPair;
        mergeLevels     1;
    }

    U
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        nSweeps         2;
        tolerance       1e-20;
        relTol          0.1;
    }

    k
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        nSweeps         2;
        tolerance       1e-20;
        relTol          0.1;
    }

    "(omega|epsilon)"
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        nSweeps         2;
        tolerance       1e-20;
        relTol          0.1;
    }
}

SIMPLE
{
    nNonOrthogonalCorrectors 0;
    numberIterationsStator 1;
    numberIterationsRotor 1;
    UMax      500;
    pMin      pMin   [0 2 -2 0 0 0 0]    -1000;
    pMax      pMax   [0 2 -2 0 0 0 0]     1000;
}

relaxationFactors
{
    fields
    {
        p               0.2;
    }
    equations
    {
        U               0.4;
        k               0.3;
        epsilon         0.3;
        omega           0.3;
    }
}