gap between boundary particle and fluid particle

I'm trying to interpret mDBC, but I'm having a problem with particle placement.

The distance between the boundary particle and the fluid particle should be Dp/2, but it is arranged as shown in the picture. I want to know how to adjust the distance between boundary particles and fluid particles. please give me advice


  • "The distance between the boundary particle and the fluid particle should be Dp/2" NO, that is not correct.

    The distance between the boundary interface should be at Dp/2 from boundary particle and Dp/2 from fluid, so exactly in the middle.

    You can get info from:

    1) XML_GUIDE_MDBC.pdf (DualSPHysics_v5.2\doc\guides)



  • thanks Alex

    I understood about 1)

    I checked the documentation of 2) and using <layers vdp ="0.5" />

    It was confirmed that the boundary interface was set to 0.5dp.

    But I want to load the stl file and apply it.

    After importing stl using <drawfilestl file> and inserting <layers vdp ="0.5" /> and simulating it, an error message appears.

    How should I adjust the boundary interface in my case?

  • Actually my case is the hydrostatic pressure case.

    As you can see, no particle touches the boundary interface.

    It seems that the particles are placed at 0.5dp intervals from the boundary interface, but I want to place them without the distance between them and the interface.

    Can you tell me how to adjust the particle placement interval?

  • You can not use LAYERS with DRAWFILESTL, that is not possible

    Please follow the examples applying mDBC to floatings as done in DualSPHysics_v5.2\examples\mdbc\09_FloatingDuck

    Same examples with STL of a cylinder and STL of ducks are explained in:


  • In fact, for your case you do not need to load an STL to create a box... use drawbox with the proper dimensions, and LAYER that can be used with DRAWBOX


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