LIGGGHTS® - User Forum

LIGGGHTS® related topics can be discussed here: discussion about models, installation, feature requests and general discussion

bcc, fcc packing in LIGGGHTS

Submitted by rahulsoni on Fri, 10/18/2013 - 14:48

I am trying to analyze the effect of packing style on the granular motion. A particular region needs to be filled by packed bed of specific style (bcc, fcc, hcp).

Is there any way or inbuilt command in LIGGGHTS to handle this task? On the other way, I think it is possible to replace the particle coordinates in dump file with the coordinates (that suits the specific style of packing)
generated by third-party package. But still, if there is a simple way to do the same?

Restore variable values for the restarted simulation

Submitted by J_Wang on Fri, 10/18/2013 - 00:31

Hello everybody,

Dose anybody know how can we restore a value defined by variable in a simulation (it is scaler defined after the simulation results) and then use the value in a new simulation? I use write_restart to save the simulation but it seems that the value defined by variables can not be saved. I can manually input the variable in the new script but it is time consuming. Any good ideas?

Jeremy

Force Chains with fix rigid

Submitted by andybond13 on Wed, 10/16/2013 - 21:09

Hello, has anyone successfully been able to calculate and visualize the force chains within a multi-sphere body?

I'm using the "hybrid granular molecular" atom style with a "fix rigid molecule" command, and am curious to see the force within the conglomerations/molecules and how that changes over time, i.e. with contacts.

raise StandardError : "no dump file specified"

Submitted by tulasiram on Wed, 10/16/2013 - 03:03

Hi,

I am trying to simulate the following code, but when I entered dump command xyz(dump("dump*")).many()
It is showing that no dump file specified . Please tell me where it went wrong.

units real
dimension 2
boundary p s p

atom_style atomic
neighbor 2.0 bin
neigh_modify delay 5

# Create Geometry
region boundary block 0 100 0 80 -0.25 0.25 units box
create_box 3 boundary
mass 1 60.1
mass 2 60.1
mass 3 60.1

gran/hertz/history/stiffness model

Submitted by jacky on Tue, 10/15/2013 - 12:18

Dear Friends,

Currently I have started to use pair_style gran/hertz/history/stiffness model in my DEM simulation.
In the LIGGGHTS manual I find that the specified parameters are multiplied by some other parameters like: the effective mass and radius, sqrt (delta n) .

I took a look on the source code and copy/paste them here:

double polyhertz = sqrt(ri*rj/(ri+rj)*deltan);

kn = polyhertz*k_n[itype][jtype];
kt = polyhertz*k_t[itype][jtype];
gamman = polyhertz*meff*gamma_n[itype][jtype];
gammat = polyhertz*meff*gamma_t[itype][jtype];

implementing "mesh/surface/stress/servo" using primitive walls

Submitted by rasoul on Sun, 10/13/2013 - 12:09

How can I implement "mesh/surface/stress/servo" using primitive walls?
I say this because in the "mesh/surface/stress/servo" command, we have to use "File Filename.stl", but I do not have any .stl file in my simulation and I control the simulation domain by primitive walls.

I am looking forward to hearing from you.

Regards,
Rasoul

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