LIGGGHTS® - User Forum

Hi all,

I would like to know how particles are placed on a wall (primitive and/or mesh). Are they put on a regular network or randomly?

Thank you guys,

Hi,
i have a question about the calculation of the contact force for particle-wall contact.
For example, if i use the Hertzian model, which radius will be inserted for the wall in the prefactor of the equation
sqrt(delta*(Ri*Rj/(Ri+Rj))*(...)?
Is the force calculated the same way, like for particle-particle-contact, at all?

Hi! i'm relatively new to liggghts, and i want to compute the contact area in a cone crusher. So far i'm using the "compute wall/gran/local contactArea" command, to store the information, unfortunately, i don't know how to use only a single mesh wall to compute the contact area.

The code that does the wall gran, computation and the dumping is:

Hi,

is it possible to calculate a variable with circular dependency?
like

variable a equal v_a+1

and I want to evaluate the variable each timestep. So I need to use the variable in a command where it is used every timestep?
Is there a smart funktion that calculates the variable every n timesteps without printing or saving the variable somewhere?

Thanks
Joshua

Hey,

it is possible to do

"compute ${omeg} all reduce ave c_atomprops[1]
compute ${vy} all reduce ave c_atomprops[2]
variable a string c_${omeg}
variable b string c_${vy}"

and also it is possible to give a string to the next:
"variable allresult string ${a}"

but why is it not possible to create a string out of two or more strings?
"variable allresult string ${a} ${b}"

doing so yields the following error:
ERROR: Illegal variable command (../variable.cpp:278)

Hi all,

I am using pair_style gran model hertz tangential history in my input script.
I am getting the following error, when i am running the simulation.

ERROR: Could not locate a fix/property storing value(s) for poissonsRatio as requested by model hertz. (../modify_liggghts.cpp:313)

Can someone please suggest, what can be the reason for this.

Thank you,

Narendra

Hi everybody,

I am trying to model a cylinder-like shape with a high length-to-diameter ratio.

The multi-sphere particle could look like this: ooooooo
So, the model would include a huge number of spheres, when I try to model several thousand of those particles.

As far as I know, liggghts also supports the application of ellipsoids in granular models, via the ASPHERE package.

Hello,
im modeling an continous mixer and have two different particle types.
I continously inserte particles at two different location and the mixed up particles leaving the mixer at the same place.
Now the problem. Because of the continously use, there are build more and more particles.
Is it possible to delete all particles, which are at the same area (exit of the mixer).
I have tried it with the delate_atome command and wasn't very successfull.

If anybody can help me. I would be very grateful.

Best regards
RobertG

Hi All,

I want to draw a cylinder, with its wall made up of particles. Is it possible to draw this in gmsh?
or please suggest any other software.

Any help will be much appreciated.

Thanks,

Narendra

Hi all,
I generate a rigid body shaped like a box with moltemplate and simulate a droptest. The problem is that the body jump's after contact with the mesh to a height that is not in relation to the physical law. k = square root (h'/h)
Restitution coefficient: 0,5
Previous height: 0,5 m
Height after first contact: 0,27756295 m
According to the formula the body should just jump to a height of 0,125m.