[mushtime]

Dear foamers,
For pressure solver, we can usually choose PCG or GAMG solver.

p
{
        solver           PCG;
        preconditioner   DIC;
        tolerance        1e-7;
        relTol           0.1;
}

p
{
solver GAMG;
tolerance 1e-06;
relTol 0.1;
smootlier GaussSeidel;
nPreSweeps  0;
nPostSweeps  2;
cacheAgglomemtion  on;
agglomerator  faceAreaPair;
nCellsInCoaisestLevel  10;
mergeLevels  1;
}

Can anyone give me suggestion on the under-relaxation factor for these two solvers?And what about relaxation factor for other field or equation?
My adviser told me that, there usually CG and AMG ways to solve the p equation. And some of the relaxation is not always the smaller the better. Usually the factor is smaller, then the simulation is more stable. But some will become unsteady if the relaxation is too small？ Can anybody give me some suggestion?
Thank you.