MMG3D Lagrangian motion: cannot maintain body shape

Hi all, I found the body surface triangles are CHANGED by the MMG3D during motion, although I have used Required/nosurf etc API functions to prevent the body surface from touching. Any suggestion?
Below is the resulted rotor blade surface

Hi Jay,

The required / nosurf tags are probably ignored during the motion step:

  • otherwise the nosurf option will avoid any displacement (because displacement are applied on boundary triangles);
  • following the same idea, the reauired triangles are used only when Mmg improves the mesh.

I suppose that you apply a displacement over the rotor blade surface? In this case, your displacement field must preserve the rotor surface.

I hope that it will helps,

Hi Algiane,
The rotor can maintain its shape at the beginning phase, while it is getting worse when rotating further.
I am sure the displacement field is correctly imposed only to the rotor surface. But you are right, the
require/nosurf seem gnored completely. It there any other way can preserve the rotor surface?

Shu-Jie LI (Jay)

Hi Jay,

Is it possible to send me:

  • a mesh and displacement with a surface rotor almost valid at the begining but degenerated after a Mmg call? (If you dont want to share your mesh, you can send it by private mail at;
  • your Mmg parameters.

I need to reproduce this issue to figure out what happens…

Thank you by advance,