[immortality]

what does momentumPredictor do in PIMPLE dictionary?have anyone some information about it?

PIMPLE
{
    momentumPredictor yes;
    nOuterCorrectors 7;
    nCorrectors     4;
    nNonOrthogonalCorrectors 1;
    rhoMin          rhoMin [ 1 -3 0 0 0 ] 0.5;
    rhoMax          rhoMax [ 1 -3 0 0 0 ] 7.5;
    convergence        1e-16;

residualControl
    {
        "(U|k|omega)"
        {
            relTol          0;
            tolerance       0.00000000001;
        }
    }
}

[immortality]

any answer is appreciated!

[santiagomarquezd]

It enables/disables the solution of the momentum predictor.

Regards

[immortality]

thanks.whats the effect of predictor on solution,accuracy and stability in unsteady compressible problems?

[wyldckat]

Originally Posted by immortality

thanks.whats the effect of predictor on solution,accuracy and stability in unsteady compressible problems?

A quick Google search lead me to this:

Originally Posted by http://openfoamwiki.net/index.php/The_PISO_algorithm_in_OpenFOAM

• Solve the momentum predictor

solve (UEqn == -fvc::grad(p));

This looks so simple that it's probably explained in any good CFD book?

[santiagomarquezd]

Hi, the momentum predictor is a first approximation of the velocity field obtained from the solution of a momentum equation assembled with the previous time-step pressure field. This velocity doesn't fulfill the restriction given by the continuity equation which is achieved laterly by the PISO method. Sometimes you can avoid the solution of the momPred saving time, but it can lead to a bad convergence in the PISO loop. Is a user's choice based in the problem behavior.

Regards.