Lennard-Jones boundary conditions


I would like to ask whether there are any versions of DualSPHysics including the Lennard-Jones wall boundary conditions. I am asking this why I am trying to simulate the coolant flow in a drill bit, but using DBC I cannot avoid wall penetration. I presume that having high velocities in small gaps is really demanding for DBC wall treatment. In the literature I found results of similar simulations, but they used Lennard-Jones. That's why I think that replacing DBC with Lennard-Jones could maybe solve the wall penetration issue for this application (I know that results would probably less accurate).

In case Lennard-Jones wouldn't be available in any versions of DualSPHysics, then I am probably going to try to implement it by myself. However, before starting it, it would be really helpful to know whether this development could conflict with other parts of DualSPHysics (inlet/outlet open boundaries or maybe something else).

Thank you very much for the help.




  • Penetration can appear if the speed of sound (Cs) or compressibility (cteB) is not properly defined.

    After checking that I will suggest to try the option of using mDBC first.


  • Hi @Alex ,

    thank you for your reply.

    I tried to increase the value of Cs (the original vaue was roughly 10 times the maximum velocity in the domain). This resulted in an improvement of the wall penetration problem, but I couldn't completely suppress it even by using a value of Cs 30 times larger than the maximum velocity. Furthermore, this led to a very strong limitation on the allowed time step size. Therefore, this approach is unfortunately not viable. I will then try to use mDBC. However, since I have rather complex geometry, it’s not easy to set up the simulation with this boundary condition. As you suggested me in an other post, I am trying to generate a second stl file with an offset of Dp/2 from the original one. I have been using FreeCAD or Salome for this purpose, but unfortunately without success. From your experience, do you have any recommendations about tools which could perform this manipulation?

    Thank you for your help.



  • New version of GenCase includes new options that will be helpful here... However we still have to prepare the documentation and examples.

    What you can do so far is to use the transformation SOLIDIFY of Blender, that one works very well!

  • Hello @Alex ,

    thank you very much for your hint. I will try it out.



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