[2538sukham]

Hi
I am trying to simulate the shot sleeve wave dynamics in high pressure die casting. There is a tutorial in Chalmers "Modeling high-pressure die casting: A
tutorial" by Sebastian Kohlstädt. I think its quite natural to use interDyMFoam as the plunger physically moves. I had the linearValveLayersFvMesh modified to account for the mesh movement without sliding. The simulations run fine however the melt height predicted seems to be higher to what is being reported in the paper.



I will attach the case files. I think the wave generation dynamics is not included in the interDyMFoam so the melt height increases in the back wall.

Any suggestions are welcomed.

pistonLayersFvMesh.C

 dynamicFvMesh     pistonLayersFvMesh;
patch movingWalls;
pistonVelocity (0.6 0 0);
minThickness 0.0005;
maxThickness 0.0010;

convertToMeters 1e-3; 
        
vertices
(
    (0 0 0) //00
    (0 50.8 0) //01
    (440.2 0 0) //02
    (440.2 50.8 0) //03
    (457.2 0 0) //04
    (457.2 50.8 0) //05
    (0 0 1) //06
    (0 50.8 1) //07
    (440.2 0 1) //08
    (440.2 50.8 1) //09
    (457.2 0 1) //10
    (457.2 50.8 1) //11
);

blocks
(
    hex (0 2 3 1 6 8 9 7) sleeve (100 25 1) simpleGrading (1 1 1) //block0
    hex (2 4 5 3 8 10 11 9) fixed (4 25 1) simpleGrading (1 1 1) //block1
);

boundary
(
    slipWalls
    {
        type wall;
        faces
            (
            (0 6 8 2)
            (3 9 7 1)
            (2 8 10 4)
            );
    }

    movingWalls
    {
        type wall;
        faces
            (
            (1 7 6 0)
            );
    }
    fixedWalls
    {
        type wall;
        faces
            (
            (4 10 11 5)
            );
    }
    outlet
    {
        type patch;
        faces
            (
            (5 11 9 3)
            );
    }
    frontAndBack
    {
        type empty;
        faces
        (
            (6 7 9 8)
            (0 2 3 1)
            (2 4 5 3)
            (8 9 11 10)
        );
    }
);
mergePatchPairs();

The simulations seems quite simple but the melt height as suggested in the paper was not attainable.


"On determining the critical velocity in the high-pressure
die casting machine’s shot sleeve using CFD" S. Kohlstädt , M. Vynnycky , S. Goeke , A. Gebauer-Teichmann. At a lost. Now I am trying to incorporate wave dynamics into the model as interDyMFoam is not doing the job.

Any suggestions are welcomed.

[2538sukham]

The piston movement is time dependent and it has been incorporated in the pistonLayersFvMesh. The layer deletion seems working fine. I will post the result as compared to the paper. Cheers.

[2538sukham]

melt height at 1.47s.png
In the paper, the back melt height at the back wall is much less as compared to the results I am getting.

[2538sukham]

I tried the boundary conditions for pressure and velocity. Now the moving wall velocity should give me a velocity normal to the moving patch. So the y-direction should have zero implied velocity. I think flux made relative in Dym codes read the U solutions and make it relative to the Wall motion prescribed. So any y-dir velocity would be made relative. Is there something I can constrain the motion or is it that I am getting these things wrong..

[2538sukham]

Originally Posted by 2538sukham

I tried the boundary conditions for pressure and velocity. Now the moving wall velocity should give me a velocity normal to the moving patch. So the y-direction should have zero implied velocity. I think flux made relative in Dym codes read the U solutions and make it relative to the Wall motion prescribed. So any y-dir velocity would be made relative. Is there something I can constrain the motion or is it that I am getting these things wrong..

Here is the case file

Aboudi_HDPC.zip

[2538sukham]

The shallow water approximations are not applied. I tried commenting out the surface tension term in the code interDyMFoam but the results were not too different. I want to compare interDyMFoam with VOF NS eq after considering shallow water approximations. Even the hydrodynamic pr case means i should specify pd=0 so that p = rho*(g.h). Any help in validation will be welcomed.

[2538sukham]

I came across a tutorial on Chalmers about depth averaged velocity which incorporates the 1D hydrodynamic cases. There is substantial difference in the way VOF is calculated. I think that's the reason why the interface height is quite higher. I will try with potentialFreeSurfaceDyMFoam and post the results. Though the melt height extraction from the result, we need to do some post processing