how to impose a rotation motion for the moving object in the case_Def.xml

Dear Sir
I want to impose a rotational motion to the object while the object is moving, so the position of the axis of the object is constantly changing. In the users guide, it only provides examples of fixed axes(Motion05: rotational motion), what can I do to impose a moving axis position in the case_Def.xml? Sincerely hope to get your help.
Thank you!


  • In a word, how to combine Rectilinear and rotation motion for a moving single object in the case_Def.xml
  • you can combine movements, there are examples in MOTION
    try and tell us if it works, please
  • edited June 2018
    Thank you, sir.
    I just tried this example in MOTION, the combination of rotation and Rectilinear motion don't work very well. There may be some problems. Can I send you the *.xml via email?
  • edited June 2018
    What is the problem with the example? Why does not it work well?
    Please send the example and its problems to my email:

    I will check it.
  • Dear jloober
    Unfortunately your email does not receive my email! Would you please give me another email address (e.g. gmail or yahoo)?
  • The problem is that when the body moves, its "rotation axis", which is denoted by "axisp1" and "axisp2", also moves.
    So, at each time step the mass center of the body should be computed.

    I do not know whether it is possible for the XML file to read the "axisp1" and "axisp2" from a file.

    I hope we receive helps from Alex.
  • edited June 2018
    Dear amir
    Thank you for your help. I also thought about the same solution. It may refer to the command ---- mvfile, but It seem that it can't read in the coordinates of the rotation axis. also, this makes the problem more complicated.
  • One solution is to compute the motions and rotations and translate them to a text file (for linear motion and rotation) and just load those files

  • Dear Alex
    Thank you for your reply. That's a good idea. But I don't know how to write this text file. None of the two commands (mvfile and mvrotfile)seem to meet the requirements, especially for rotating characters, the moving axis can't be read in.
  • I am expecting to receive an answer from Alex!
  • We have just replied to your email.
    We have sent an example.
    However you also can find a similar example in DualSPHysics_4.2_package/examples/motion/Motion03.xml
  • It's perfect. thanks Alex and Amir, thank you everyone!
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