CFD Online Discussion Forums - fully developed turbulent flow at inlet using mapped BC

Hello All,

I am trying to simulated particle-laden backward facing step (BFS) case using DPMFoam. I am using mapped BC to provide fully developed turbulent flow at inlet (with centreline velocity as 10.5 m/s and average velocity as 9.39 m/s. To map the flow field, I am taking offset of 0.067m from inlet but unfortunately I am not getting fully developed flow at inlet with centre-line velocity as 10.5 m/s and average of 9.39 m/s. The peaks of mapped velocity at inlet is is 11.13 m/s *more than 10.5 m/s) and also the mapped velocity field does not satisfy no-slip condition (velocity at the wall are not zero). the the settings for mapped BC are as follows:

In blockMeshDict:

Code:





    inlet

    {

        type            mappedPatch;

        sampleMode      nearestCell;

        sampleRegion    region0;

        samplePatch     none;

        offsetMode      uniform;

        offset          (0.067 0 0);





       /* type    patch; */

        faces

        (

            (4 7 3 0)

        );

    }

In U.air

Code:

 



inlet

    {

        type                mapped;

        value               uniform (10.5 0 0);

        interpolationScheme cell;

        setAverage          true;

        average             (9.39 0 0);

    }

In omega.air

Code:

inlet

    {

      /*  type                zeroGradient; */

          type                mapped;

          value               uniform 129.448;

          interpolationScheme cell;

          setAverage          true;

          average             129.448;

    }

In k.air

Code:

inlet

    {

       /* type            zeroGradient; */



        type                mapped;

        value               uniform 0.331;

        interpolationScheme cell;

        setAverage          true;;

        average             0.331;

   }

I am also not sure about the meaning of certain keywords(value, average) used in mapped BC. I am hoping to get some idea about mapped BC to provide fully developed turbulent flow at inlet.

Best Regards
Atul