LIGGGHTS® - User Forum

Hi,

I need the average pressure between the particles. I tried two ways with exact the same results. compute pressure for all atoms using the temperature from a compute temp and compute stress/atom for every single particle and sum these with compute reduce. What would be faster? Is there a difference in speed between compute reduce sum and the variable sum() command?

Regards,

Paul

Hi,

I want to generate a dense packing with fix insert/pack and particle growing. This is very common and no problem with fix adapt. The growing ends when the particles have a reached a given pressure. The pressure is calculated by compute pressure. Since I have a lot of particles and slightly CPU I wonder if there is something new in interrupting a run when a special event occurs to save CPU time? Or is run N every n, check with if and going on else dump results and quit still the preferred solution?

Regards,

Paul

I am using LIGGGHTS on a bluegene/p cluster and when I attempt to run a simulation I get an error that reads:

Could not locate a fix/property storing value(s) for youngsModulus as requested by gran/hooke. (modify_liggghts.cpp:247)

I checked with the sysadmin and he has told me that there is nothing wrong with the installation. I have version 2.3.5 installed. Any help or direction at all would be greatly appreciated.

Hi,

I am wondering how the adhesion between the particles and the wall is treated. I have set up my simulation with 3 different types, 1 is the particles, 2 is the walls, and 3 is for a no friction/no adhesion symmetry plane. I have specified the cohesion as:

fix m6 all property/global cohesionEnergyDensity peratomtypepair 3 &
1000000 1000000 0000001 &
1000000 0000001 0000001 &
0000001 0000001 0000001

I am using the sphere type for the granular simulation, how could I include the potential force in the simulation? I tired us the Pair_style hybrid gran/hertz/history lj/cut 2.5. But I get an error message” pair hybrid sub-style is not used”. Can someone help me out? thanks in advance

I typically use the fix_nve integration (only updates position and linear velocity) for my granular simulations as this gives a good approximation of blocky (angular) material behaviour. I am wondering if the sjkr cohesion model can be used with this integrator or do I need to use fix_nve_sphere to get cohesion?

In the mean time, I am making a little test model.

Thank you,

Kirk

Hi,

playing around with the dump image command I came over a restiveness. I inserted some atoms in a lattice with create_atoms, and changed diameter to 0.2 by set command. Computes and dump local/custom are working like expected. The command dump image ignores diameter and uses 1.0, after dump_modify adiam it works as well. Is it because of using create_atom?

Edit:

Dear guys:

I am new to this forum, and I would like to seek some help in the compilation of LIGGGHTS

When I compiled LIGGGHTS using "make openmpi", I encounter the following error messages:

Good morning,

I would like to make a model using the fix mesh/surface/stress/servo command. I was wondering if someone would be willing to share a little example simulation that includes this command?

Thank you in advance,\

Kirk Fraser

Hi all,

I want to simulate a belt conveyor with ribs on the surface. (stl attached)
For a flat belt i would usually use the surface_vel command to specify the imported mesh as conveyor belt.
The Problem about this command is that there is no motion of the ribs. Think this behaviour is expected.