CFD Online Discussion Forums - simpleFoamResidual

Hi all,

My question is related to the utility simpleFoamResidual implemented into OF1.6ext. According to the code, it analyze the momentum equation. The perfect situation, I think, would be that uResidual is equal "0".

The attached convergence is OK but the maxium uResidual that I obtain is around 76 and the mean around 0.09. In other different mesh, the maximum uResidual obtained was around 2000.

Could anyone tell me how much is a high value of uResidual? Is possible to have a physical meaning about the uResidual? If I have higher values than 0.05, for example, does it tell me that it is require to refine the mesh?

I would appreciate any help. I would like to have a criteria to know if current mesh resolution is enough or not for my purposes without doing a mesh resolution analysis in detail. Thank you very much.

Code:

            Info<< "    Calculating uResidual" << endl;

            volScalarField uResidual

            (

                IOobject

                (

                    "uResidual",

                    runTime.timeName(),

                    mesh,

                    IOobject::NO_READ

                ),

                mag

                (

                    fvc::div(phi, U)

                  + fvc::div(turbulence->R())

                  + fvc::grad(p)

                )

            );

Code:

Time = 3000



DILUPBiCG:  Solving for Ux, Initial residual = 1.48121e-08, Final residual = 6.66887e-11, No Iterations 2

DILUPBiCG:  Solving for Uy, Initial residual = 1.09835e-05, Final residual = 1.32954e-08, No Iterations 2

DILUPBiCG:  Solving for Uz, Initial residual = 1.96974e-05, Final residual = 3.96294e-08, No Iterations 2

GAMG:  Solving for p, Initial residual = 0.00085226, Final residual = 4.08688e-05, No Iterations 8

time step continuity errors : sum local = 2.32144e-10, global = -6.39797e-11, cumulative = 2.45607e-07

DILUPBiCG:  Solving for epsilon, Initial residual = 2.62941e-07, Final residual = 2.54438e-10, No Iterations 1

DILUPBiCG:  Solving for k, Initial residual = 9.73059e-07, Final residual = 3.07595e-10, No Iterations 2

ExecutionTime = 7790.51 s  ClockTime = 7792 s