how to limit particle motion in z direction (3d to 2d)

Submitted by solient on Tue, 08/28/2018 - 20:30

Dear all,

Now, I have settled down all particles on the surface (large size distribution and shape distribution) and begin to start the simulation from the restart file.

I set the gravity as the Y direction and want to make particles only move in x-y plane. But I do not know how to let particles do not do any motion in z direction. It seems that fix/setforce does not work.

Are there any suggestions?

Looking forward to your kind help. Thank you very much in advance.

Best wishes,
Solient

Forums:

Rachel | Fri, 08/31/2018 - 01:01

Hi paul,

Thanks for your response. One more question, as I see from the "dimension" command, the particle will still be treated as a sphere, not a 2d circle. Does that mean only one particle exist along the z direction if we set a x-y plane 2d system? Then how can we visualize such particle in PARAVIEW and how can be calculate the void ratio of the system?

paul | Fri, 08/31/2018 - 10:36

For 2D simulations, liggghts will still consider the particles 3D, but confined to the xy plane.
The dumps will still have a constant z coordinate, so it will be nothing special to paraview. (paraview can also handle 2d data, regardless)
Look at the sph2 example - it uses the combination of dimension and fix enforce2d.

Have you tried fix ave/euler for voidfractions?

solient | Fri, 08/31/2018 - 15:22

Thank you very much for your suggestion. But I still have a question. In my case, the particle has a large distribution of particle size and shape (from XRD scan), does 2D still works well?

Many thanks.

Best regards,
Solient