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actual flow rate not match the designed flow rate in ventilation modeling

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Old   November 18, 2018, 07:10
Default actual flow rate not match the designed flow rate in ventilation modeling
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Pu Gong
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Hi foamers

I am doing a displacement ventilation modeling of a single office with a seated occupants which generating heat thermal plume using buoyantBoussinesqPimpleFoam. The inlet and outlet size are both 0.2×0.2=0.04m2, the inlet velocity is 0.25m/s, hence as my expect the volume flow rate of inlet (designed flow rate) and outlet should be 0.01m3/s, or 10L/s.

However, the actual volume flow rate result from flow rate monitor is 9L/s.

Anyone please help how can I make the actual flow rate the same as designed value?
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Old   November 18, 2018, 08:11
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Peter Baskovich
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Are you using fluxCorrected boundary conditions?
Please post more info, whole case is good in a zip or post the 0 folder and boundary files to start with.
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Old   November 18, 2018, 12:37
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Pu Gong
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Quote:
Originally Posted by pete20r2 View Post
Are you using fluxCorrected boundary conditions?
Please post more info, whole case is good in a zip or post the 0 folder and boundary files to start with.
Hi Peter

Thanks for your reply. Please check my U, T and P-rgh files.
And what you mean by the fluxCorrected boundary condition? Is it a inlet outlet boundary condition that can be identified in the U file?

Cheers

Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform (0.25 0 0);
    }
    outlet
    {
        type            inletOutlet;
        inletValue      uniform (0 0 0);
	value           uniform (0 0 0);
    }
	top
    {
        type            noSlip;
    }
    bottom
    {
        type            noSlip;
    }
    wall
    {
        type            noSlip;
    }
    desk
    {
        type            noSlip;
    }
    human
    {
        type            noSlip;
    }	
}

// ************************************************************************* //
Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 1 0 0 0];

internalField   uniform 298.15;

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform 298.15;
    }
    outlet
    {
        type            fixedValue;
        value           uniform 298.15;
    }
    top
    {
        type            fixedValue;
        value           uniform 298.15;
    }
    bottom
    {
        type            fixedValue;
        value           uniform 298.15;
    }    
	wall
    {
        type            fixedValue;
        value           uniform 298.15;
    }
    desk
    {
        type            fixedValue;
        value           uniform 298.15;
    }
    human
    {
        type            fixedValue;
        value           uniform 298.15;
    }	
}

Code:
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p_rgh;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform 0;
    }
    outlet
    {
        type            fixedValue;
        value           uniform 0;
    }
    top
    {
        type            fixedFluxPressure;
        rho             rhok;
        value           uniform 0;
    }
    bottom
    {
        type            fixedFluxPressure;
        rho             rhok;
        value           uniform 0;
    }
    wall
    {
        type            fixedFluxPressure;
        rho             rhok;
        value           uniform 0;
    }
    desk
    {
        type            fixedFluxPressure;
        rho             rhok;
        value           uniform 0;
    }
    human
    {
        type            fixedFluxPressure;
        rho             rhok;
        value           uniform 0;
    }
}
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