LIGGGHTS® - User Forum

Hi all,
I think there are some problems with the implementation of the tangential spring in the pair_style gran/hooke, especially for soft particles where the overlap between the particles gets high.
So far the relative rotational velocities between 2 particles are calculated by using the radius of the particles:

wr1 = (radi*omega[i][0] + radj*omega[j][0]) * rinv;

The force application point for the tangential forces also lies on the radius of the particles:

torque[i][0] -= radi*tor1;

Hi all!
The region command in liggghts is static but it becomes dynamic when we apply wiggle command. Is this possible that we apply the wiggle command but the region should remain static. Can anybody help?
sajjad

Hi all,

I have this small error when I run my simulation :

85589 atoms
82223 atoms in group A
3366 atoms in group B
ERROR: Length not sufficient for variable youngsModulus

Do you know thir error ? How can I resolve this error ?

For information, if there is only one group of atoms (i.e., 85589 atoms in group A), the simulation runs.

Regards
JF

Ps: the Youg's modulus is defined for all groups (i.e., fix m1 all property/global youngsModulus peratomtype 1.e5)

Hi,
Why I can not find same scales of mesh object in LIGGGHTS when I import it made in Maya? I created mesh in cm in Maya and export it in STL. Then import the same in LIGGGHTS but it doesn't show the same scales of hight and diameter as that of Maya's. I have to rescale the object in LIGGGHTS for required scales. It takes a lot of time. Furthermore, height-diameter ratio will not remain same when it was in Maya.
Thanks,
Ram

Hi all,

I have the objective to modify the neighbor class in order to load a neighbor list via a text file. I need your opinion to do this in compliance with the previous developments in LIGGGHTS. The interest is to extend LIGGGHTS to perform lattice beam simulations.

Therefore:
I am thinking to add a new style : enum{NSQ,BIN,MULTI,TXT} in the files : neighbor.cpp and neigh_list.cpp

I am thinking to add a new request: int latthistory in the file neigh_request.cpp

Hi,

I am creating spheres so that they initially intersect with walls. I get the following message

WARNING: Dangerous build in triangle neighbor list.

What is the consequence of this? I am getting a memory error I don't understand and I wonder if this is the reason...

Thanks for all the help,
George

Hi all,

I want to simulate a granular flow in a shear cell. Therefore I have a axis-symmetric geometry. To save computing time I want to simulate only a quarter of the ringshaped geometry by using quarter periodic boundary conditions in angular direction. Is there a possibility to use such a boundary condition in the current build?

Thanks
Yansan

Dear LIGGGHTS developers,

I looked several times under the download section for the git address of LIGGGHTS download, but, could not find it. Could you please tell me where I find the git address? Thanks!

Pei-Ying

Hi all,

I wonder if it is possible to introduce a directional bond between particles. Unlike cohesion, Im looking for some kind of bonding which is effective when there are contacts only in specific directions of the particles.

Thanks,

Ozgur

question:

fix 1
run 1000 upto

unfix 1
fix 2
run 2000 upto

unfix 2
fix 1
run 3000 upto

unfix 1
fix 2
run 4000 upto

unfix 2
fix 1
run 5000 upto

repeat ..

I want to know what command or skills may use for the alternate cycle as above example. Welcome any suggestion or advise.

thank you in advance.

best regards,
xinze