LIGGGHTS® - User Forum

Hello,

I seem to be having a problem using the fix wall/region command. My simulation entails building a trapdoor mechanism at the bottom of a region filled with grains. Thus far, I have created the mechanism by generating three "thin" regions that lie next to each other and act as the floor, and then applying the fix wall/region command to each of them to create the walls. My plan is to unfix the middle region at some stage, and the trapdoor mechanism would work.

Hi everyone,

Please take a look at the attached file, it is a picture with two images. The one of the left side is a simulation using series process. The one of the right side is a simulation using parallel process (processors 2 2 1). As you can see, the last one has a lack of particles due to the division of processors. Is it normal this situation?

Regards

Hi everyone,
I'm trying to load a restart file but it keeps error-exiting when I fix my mesh surfaces. I have the original input file that created the restart state, I've checked the log that was output for this case, and as far as I can tell I am specifying the exact same fix properties with the restarted input file.

Hi all,
Sometimes the fix particledistribution doesn't work properly, it only inserts the bigger particle. I was changing some values like massrate, extrude_length, velocity, insertion face, and other, in order to insert all type of the particles that I want. I managed to do it using trial and error, but I don't think that is the best way. So I have two questions:

is there any other way solve this? please show me your method

what does the key seed in fix insert/stream? I've read it in the manual but there is not no too mush information about it.

Hi, All:

I am currently running LIGGGHTS simulation test on a large cluster, if there is no limitation on number of nodes and processors per node, I have two companion questions:

1. Does anyone have an idea how many particles that LIGGGHTS/CFDEM is currently able to simulate?
2. When we do multi-processor simulation, how many number of particles is a reasonable number for one processor?

Thanks for any suggestions in advance!

Roy Li

We are using LIGGGHTS to generate particle flow streams in belt conveyor/transfer chute analyses. A few of our people have noticed an odd behavior with particles becoming "stuck" to the drive pulley, and as of yet, we've been unable to find what we've done incorrectly. Below you will find links to two videos, generated by our own post-processor. Forgive me for the partial results as a bug with STL files prevents the system components (belts, chutes, pulleys) from being displayed, but the particle flows are displayed correctly.

Hi all,
I've been trying to use the variable command in order to get the position of one particule in every timestep. I haven't been able to store the position of them but I have been able to store other variables like mass, time and number of particles that cross a region.

here is my input script (in this one there is just one particle) , please tell me what is wrong with it.

I'm trying to get a nice bed of particles for a simulation, but I'm having difficulties getting the particles in there correctly.

As can be seen in the attached image, plenty of particles are inserted, but they are piling up in the middle, and not really filling the volume (this image is some 50000 timesteps after insertion is unfixed, nothing else happens).

I'm trying to get a rectangular volume filled, with a reasonably flat surface.

I'm currently using insert/pack:

HI

Before I proposed my question, I have searched the forum, I got some useful information, but I still have some problems.

I need to use two or more types of granular materials (glass, iron ball), so I need to set the Youngmodulus, Poission Ratio, etc for both materials.

From the older topics in the forum, I found that it is NO need to use 'create_atom' command to create 1 and 2 types atoms. Instead, directly to use