LIGGGHTS® - User Forum

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

Variable conveyor speed

Submitted by RocheDEM on Thu, 08/08/2013 - 16:15

Is there a simple way to change the speed of a conveyor (surface velocity).

The only thing I can think of is to start with one fix mesh/surface with a certain surface velocity. stop the simulation and write a restart file.
Restart the sim with a new surface velocity...

I'm sure there is a better way though.

Thank you for your help,

Kirk

Restarting with a different numer of processors?

Submitted by RocheDEM on Wed, 08/07/2013 - 15:30

Hi,

I have been running my simulations with 2 cpu's and I use

write_restart restart-%-*.rstrt

to create a restart at the end of the simulation.

I was wondering if I can restart with a different number of cpus. I would like to use 6 now. my read_restart looks like

read_restart restart-%-*.rstrt

Whould I have more luck if I used

write_restart restart-*.rstrt

and

read_restart restart-*.rstrt

instead?

Thank you,

Kirk

Does Liggghts support inserting particle during CFD-DEM coupling?

Submitted by keepfit on Tue, 08/06/2013 - 17:41

Hi Chris,

My question is pretty much same as the title. To explain in more detail (please also take a look at this post: http://cfdem.dcs-computing.com/?q=node/1745 ), the following command is used to insert particle steam:

fix ins nve_group insert/stream seed 5330 distributiontemplate pdd1 &
nparticles 20000 particlerate 8000 overlapcheck yes vel constant 0.0 5.0 0.0 &
insertion_face inface extrude_length 0.02

Trouble restarting

Submitted by RocheDEM on Tue, 08/06/2013 - 15:00

Hi,

I am working on a shear cell simulation. I run the simulation in different steps (filling, cleaning, shearing...). The problem is that after I finish the shearing operation, I noticed that I have not attained steady state for the shear force. I want to restart (this is the 3rd restart that this model will see). The model will not restart from this point. I have included all the files needed to (try to) run my model. I get the following error:

cumulative rotation and sliding

Submitted by mojgan on Mon, 08/05/2013 - 19:27

hi everybody,
I was wondering if there is any way of calculating cumulative rotation of particles through the scripting. I do not want to change the source code and I think that its postprocessing will be so time consuming as particles data should be saved in all steps. moreover, I need to know which particles slide against their neighbors. how can I overcome these problems?

thank you so much
mojgan

How to get the weighted pressure of the particles?

PaulWinkler's picture
Submitted by PaulWinkler on Thu, 08/01/2013 - 19:49

Hi,

I need the average weighted pressure of the particles. Using compute pressure and compute reduce of compute stress/atom I get the same result. In Liggghts this formula is used:

I am looking for something like:

using

What is the pressure Liggghts calculate with compute pressure? Why does it differ from a the pressure on the walls of the particles? Can anyone please give a hint?

Regards,

Paul

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