Using mDBC for multiple MK?


So currently one can use mDBC for both simple and complex objects. One can apply mDBC directly on planes, cylinder and a specific set direction. But as far as I can see, I cannot yet have two different complex geometries, and treat them independently, i.e. using different MK values?

This is because we are only able to use on geometry file as of now - could it be possible in the future to use more of these?

Or have I misread some documentation?

Kind regards


  • Not sure what you mean...

    Let me help with this: mDBC will be only applied to the geometries you define using the two approaches (page 4 of XMLGUIDEMDBC.pdf).

    Therefore in the method 1 only the objects you include in "[CaseName]-hdp-Actual.vtk" will be used to create normals so that mDBC, the rest of objects that you have not included there will be treated using DBC


  • Hi Alex!

    What I mean is that, if I have two complex objects which I need to generate normals for, I have to combine them under 1 geometry file. This means I have to assign each of them the same mk value, as done in your guide.

    I would like if it was possible to have multiple objects, with different mk's, to have their own geometry file each in some cases.

    Kind regards

  • not sure if we have an example for what you mean.... but you can have different objects...

    perhaps in the case of dambreak3d... there are two objects (not complex but...) the tank and the obstacle... and we compute normals for the two...

    please check that example in case that is what you need...

    sorry, if again I have not understood your case...

  • edited September 17

    Hi no problem, I will try to explain it again, sometimes I am a bit too fast in my explanations!

    Basically, looking at documentation, we are in the case of the sloshing generating an outer and inner box (i.e. "complex shapes"):

    To do this the code is as follows:

    Note how both the tank and obstacle is drawn using mk=0. Then this forces us to have both object under mk=0, when drawing the actual particles:

    So this is where my complaint lies; When working with multiple "complex shapes", I am forced to draw it all under one mk (in this case, mkbound = 0), else it will not work with geometry file:

    I therefore hope in a future version we will be able to use multiple mk / geometry files, so that post-processing is much easier when we have split it into correct mk values :-)

    Kind regards

  • You can use different mk, no problem with that!

    That is not important when creating the actual geometry but you can use different MK when creating the particles.

    This example of sloshing tank was using the same MK since in this example we define the same sloshing motion for objects with the same MK.

    Please try to use different MK since that is not restriction

    @jmdalonso can you confirm this?

  • @Alex thanks for clarifying I can confirm it is possible! I went through the examples and 04_dambreak under mdbc shows how to. I just got confused by the documentation.

    Kind regards

  • yes, that is the example I suggested you before

    let us know if find more problems


  • Of course! I really enjoy digging in this, especially with the new mDBC, I see much better results near walls than before.

    Kind regards

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