CFD Online Discussion Forums - a room mechanical/natural ventilation case

Hi Foamers,
I'm trying to set a mechanical/natural ventilation case, concerning a ship engine room. I don't need to model fans and other devices, just inlet and outlet openings. I'm new at ventilation problems, so I'm tackling the problem gradually. I've already looked for similar cases here and I'd like to share my little experience step by step. I started with the simpleFoam solver for earlier tests, but I think that I'll use buoyantBoussinesqSimpleFoam later.
The attached picture show the simple test domain: a cubic room with three openings: inlet (on the left) and outlet (on the top) with mechanical ventilation systems and a window for natural ventilation (on the right).
The turbulent model k-epsilon model is adopted. I guess a velocity fluctuating component of 5% of U and a turbulent length scale of 0.038*Dh (hydraulic diameter). The following boundary conditions are set:

U
INLET
type flowRateInletVelocity;
volumetricFlowRate constant 0.5;
value uniform (0 0 0);
OUTLET
type flowRateInletVelocity;
volumetricFlowRate constant -0.2;
value uniform (0 0 0);
WINDOW
type inletOutlet;
inletValue uniform (0 0 0);
value uniform (0 0 0);
WALL
type fixedValue;
value uniform (0 0 0);

p
INLET
type zeroGradient;
OUTLET
type fixedValue;
value uniform 0;
WINDOW
type fixedValue;
value uniform 0;
WALL
type zeroGradient;

epsilon, k
INLET
type fixedValue;
value $internalField;
OUTLET
type zeroGradient;
WINDOW
type zeroGradient;
WALL
type epsilon(or kqR)WallFunction;
value $internalField;

I used the following numerical schemes

Code:

ddtSchemes

{

    default         steadyState;

}



gradSchemes

{

    default         Gauss linear;

}



divSchemes

{

    default         none;

    div(phi,U)      bounded Gauss upwind;

    div(phi,k)      bounded Gauss upwind;

    div(phi,epsilon) bounded Gauss upwind;

    div(phi,R)      bounded Gauss upwind;

    div(R)          Gauss linear;

    div(phi,nuTilda) bounded Gauss upwind;

    div((nuEff*dev(T(grad(U))))) Gauss linear;

}



laplacianSchemes

{

    default         Gauss linear corrected;

}



interpolationSchemes

{

    default         linear;

}



snGradSchemes

{

    default         corrected;

}



fluxRequired

{

    default         no;

    p               ;

}

and solution and algorithm controls

Code:

solvers

{

    p

    {

        solver          PCG;

        preconditioner   DIC;

        tolerance       1e-09;

        relTol          0.1;

    }



    "(U|k|epsilon|R|nuTilda)"

    {

        solver          PBiCG;

        preconditioner   DILU;

        tolerance        1e-09;

        relTol           0.1;

    }

}



SIMPLE

{

    nNonOrthogonalCorrectors 0;



    residualControl

    {

        p               1e-2;

        U               1e-3;

        "(k|epsilon|omega)" 1e-3;

    }

}



relaxationFactors

{

    fields

    {

        p               0.15;

    }

    equations

    {

        U               0.005;

        k               0.001;

        epsilon         0.001;

        R               0.001;

        nuTilda         0.001;

    }

}

I'd like to have your suggestions, remarks and corrections about my choice of turbulent model, initial turbulent settings, boundary conditions, fvSchemes, fvSolution. Thanks for your attention and your help.