Dear all,

I am running the timestepper of the IncNavierStokesSolver for a Quasi-3D problem in parallel. As I mentioned in a previous email, the default combination of linear solver and preconditioning (allegedly IterativeStaticCond) seems to be producing non-physical oscillations in the pressure field.

I have tried to follow the suggestion that non-default settings (and different for velocity and pressure fields) like those specified in the user guide as an example might improve the situation:

<GLOBALSYSSOLNINFO>
    <V VAR="u,v,w">
        <I PROPERTY="GlobalSysSoln"                    VALUE="IterativeStaticCond" />
        <I PROPERTY="Preconditioner"                   VALUE="LowEnergyBlock"/>
        <I PROPERTY="IterativeSolverTolerance"     VALUE="1e-8"/>
    </V>
    <V VAR="p">
        <I PROPERTY="GlobalSysSoln"                    VALUE="IterativeStaticCond" />
        <I PROPERTY="Preconditioner"                   VALUE="FullLinearSpaceWithLowEnergyBlock"/>
        <I PROPERTY="IterativeSolverTolerance" VALUE="1e-6"/>
    </V>
</GLOBALSYSSOLNINFO>

These preconditioners seem incompatible with Quasi-3D discretisations and the solver crashes with an error. I have tried different combinations but the only that seems to be working is Diagonal for "u,v,w" and FullLinearSpaceWithDiagonal for "p". Are these the defaults when a mere IterativeStaticCond is specified in SOLVERINFO or nothing is said at all? If so, what are the default values for IterativeSolverTolerance? Are these tolerances the same for velocity and pressure fields? Is there any other preconditioning option that I can use with quasi-3D problems?

Cheers