LIGGGHTS® - User Forum

Hello, I've done a few simulations trying with 1, 4 and 8 processors, and I got higher calculation time for 4, and even more, for 8 processors. In the input script, I tried two thing. First I didn't set any parameter for "Processors", and then I try with several combinations. I noticed that I could get better calculation time chosing aproppiate values in "Processors", but it is not better than a single processor. I read the recomendations in the manual where is explained what to do to get better performance.

I want to calculate residence time distribution of a system. I used the following lines in the script:

region rtd block 0 0 0 0.01 0 0.01 units box
fix rt all property/atom/tracer region_mark rtd mark_step 1000 marker_style dirac check_mark_every 1000
compute nparticles all nparticles/tracer/region region_count rtd tracer rt
fix extra all print 100 $nparticles file rttd.txt

but this error occurs:
ERROR on proc 0: Substitution for illegal variable (input.cpp:410)

Dear LIGGGHTS users,

I have a simple problem related to dump custom command.
I have defined a per-atom vector which has 12 elements. I perform some calculations on this vector and want to dump it out, however I get the following error.

"Dump custom fix ID does not compute per-atom vector"

This is the input script commands I use:

fix LB all property/atom LB vector yes no no -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
dump dmp all custom ${nDump} dump.${OutName} id type f_LB[1] ....f_LB[12]

Dear all,

Happy new year 2015 to all members,

To start a new year, I would like to be clarified concerning a solution to convert dump/local output to VTK file. Looking into several discussions in terms of this issue, I am enable to have EVTK and dump2forcenew.py ( or dump2force.py by Mark Bentley) routine however the running come out with error:

File "...LIGGGHTS/mylpp/src/dump2forcenew.py", line 74, in
if forcedata.snaps[fileindex].natoms !=0 and len(forcedata.snaps[0].atoms[0]) != 11:
IndexError: list index out of range

Is LIGGGHTS enable to model the fracture of particles? such as what happens in a ball mill?

Hi, All:

I was trying to use the dynamic load balancing of LIGGHTS to minimize the computational time. I found the following document: http://cfdem.dcs-computing.com/media/DEM/benchmarks/LIGGGHTS_Benchmarks.pdf, the LIGGGHTS version I am using is: Version LIGGGHTS-PUBLIC 3.0.6

However if I try to use the load balancing command (e.g. in page 43 of the document) :

fix lb all balance 0 xyz 10 1.1 out balance.txt

The program prompts the error:

Hello, can you give me any info about how to use multiprocessing in Liggghts 3.0.6? i mean, usually in 3.0.2 i was using mpirun for 4 my procs and it worked well! and after the installation of the new version, it does not work anymore... is something changed? Thanks for your answers!

Dear all,

I am simulating two spheres (sphere1 and sphere2) which are dropped in rotating cylinder.

I'm looking for a command that give me the total number of interaction that sphere1 participates(total number of interact with wall and with sphere 2) .

I tried the commands (compute wall/gran/local id …..and pair/gran/local id and then dump local), but I got the IDs of particles in contact at each timesteps.However I am looking for the total number of interactions.

Thank you in advance.

Best,

Abdul

Hello everyone,

I'm trying to pack rashig rings to create a packed bed reactor.
I don't know from where I have to start. I have an STL of the ring, I think I have to create a clump of that shape and then use the multisphere particle template. Is it right?
I'm not able to create the dump file from the STL, can anyone help me?

Any hint or suggestion is very helpful

Thanks

Hi all,

As we all know, neighbor cutoff = force cutoff+skin. However, I don't know how LIGGGHTS determines the force cutoff value.

Are there any command in LIGGGHTS that we could use to modify force cutoff (haven't found anyone yet)?

Best regards,

Su