LIGGGHTS® - User Forum

Hi,
Is there a way to turn off the interaction between a frictional wall (imported using "fix mesh/surface") and a selected group of atoms in a simulation? I want the wall to act as boundary only for some atoms in the simulation and not for others based on the atom type. I tried using the "neigh_modify exclude" command but it does not seem to work for walls.

Any suggestions would be appreciated.

Thanks,
Tapan

Hi,

I just pulled the latest version (2.0.6), the particles are now changing temperature due to the hot conveyor. I have attached a little mpeg for anyone that is interested. Happy to have this working now!

Thank you,

Kirk

I just noticed that coord/gran doesn't appear in LIGGGHTS 2.0 - is this a feature that will be re-integrated, or was it removed deliberately?

Thanks! Mark

Hello,

I believe there is an error in shear modulus formula in the manual for pair_gran. Instead of

1/G*=2(2+nu1)(1-nu1)/Y1+2(2+nu2)(1-nu2)/Y2

there should be

1/G*=2(2-nu1)(1+nu1)/Y1+2(2-nu2)(1+nu2)/Y2

If we take two equal materials so nu1=nu2=nu and Y1=Y2=Y then accordind to your formula G*=Y/[4(2+nu)(1-nu)] and k_t=8G*=2Y/[(2+nu)(1-nu)], however according to the literature, k_t=2Y/[(2-nu)(1+nu)].

Hi,

I ran my case again with the latest version of liggghts (2.0.5), the analysis runs to completion without any errros.

When I postprosess the results, there does not appear to be a change in temperature due to the particles contact with the hot conveyor. Is there something that I need to change in my input script to have heat transfered from the hot conveyor to the particles?

Thank you,

Kirk

Dear all,
I would like to simulate a macroscopic object in contact with a granular system,
sort of a rotating ratchet.
I have the mesh and can insert it in my simulated granular system, but I would
like to have it "fixed" in space, and rotating around one (fixed) axis.
Basically I would need a mesh/gran/1dof fix :-)
I have solved translations by applying a strong spring that does not allow
my mesh to move away. However, it does still rotate with 3 dof, and I would
like to have just one.
Any suggestion/ideas/comments?

Hi everyone,
I am trying to install LIGGGHTS on Ubuntu 10.04. I notice that there is a folder named lmp_fedora which is important, however, I could find it in LIGGGHTS/LIGGGHTS-PUBLIC/src. In LIGGGHTS/LIGGGHTS-PUBLIC/src, there is just a file named lmp_fedora, and a folder named Obj_fedora.

I want to ask whether the folder of lmp_fedora is created by the step of make fedora? And if not, how should I do to create this folder?

Hi all,

I have a simulation comprising 250k particles of ~100 µm diameter packed loosely between two concentric cylinders. The packing is read from a file with read_data, and I simply want to let the packing settle under gravity for now (gravity is along the axis of the cylinder). I have two mesh walls defining the inner and outer cylinders, and as in the attached images no particles are in contact with the walls.

hi
I've got an experimental data-file containing coordinates of spherical grains, however there are some wrong overlaps between these spherical grains, i have tried to import this data file into the liggghts and let the package relax, so the overlaps are gone,
I have used fix_nve/sphere but the overlaps make the grains going on an exploding manner, even if i reduce the time-step, the same thing happens but in a longer time,
I have used fix_nve_limit and everything looks fine: after a little displacement the grains settle down,

I haven't seen much mention of this on the forums yet, but if anyone hasn't noticed LIGGGHTS 2.0 includes the ability to script LIGGGHTS from python, which can be very useful for building more complex run-time analyses, graph ongoing simulations, build a GUI to control certain aspects etc. etc.