CFD Online Discussion Forums

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   OpenFOAM Running, Solving & CFD (https://www.cfd-online.com/Forums/openfoam-solving/)
-   -   actual flow rate not match the designed flow rate in ventilation modeling (https://www.cfd-online.com/Forums/openfoam-solving/211736-actual-flow-rate-not-match-designed-flow-rate-ventilation-modeling.html)

minecraftgp November 18, 2018 07:10
actual flow rate not match the designed flow rate in ventilation modeling
 
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?

pete20r2 November 18, 2018 08:11
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.

minecraftgp November 18, 2018 12:37
Quote:
Originally Posted by pete20r2 (Post 716050)
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;
    }
}


All times are GMT -4. The time now is 17:36.