LIGGGHTS® - User Forum

Hi everyone,

I noticed that a lot of papers suggested reducing Young's modulus (shown in Hertz contact model) by several orders in Engineering modeling. But I didn't find any guideline on how many orders are proper in doing this, especially for a binary system. Can anyone give me some reference? Thanks.

Dear Liggghts users,

I am having three problems counting the number of particles of 2 different sizes flowing through a rectangular slot. My Liggghts version is 2.3.6.

The first problem is that when I use group function with variable function as shown below in the input script, the output of particle count is always zero. I don't quite understand why this happens. (Here I simplify the problem by using fewer timesteps and try to count to particle in the insert region, named as inbox.)

Here is the script I wrote:

Hello,
I'm new at Liggghts. So far I worked with the continuous mixer tutorial.
After a few tries and errors, I managed it, to work under Liggghts 3.0.3.
At the moment I try to get the time of creation of every particle to be written in the dump file.
I searched for some clues, but I didn't find anything.

I hope somebody can help me.

Thanks.
RobertG.

Dear Colleagues,
I would like to esxport the displacement of the moving mesh when using commmand fix mesh/surface/stress/servo. Is there a way to do this?
Thank you.
Best regards,
ZYan

Hi users

I am a new user of the LIGGGHTS, and i work in my resource with this program. I have a questions, How can i install molecular package? I need to work with ellipsoid for my resource, and i have read that others users have created codes for this atom style but the program needs the molecular package. Thanks very much

Dear colleagues,
There are many tools to generate .stl mesh., i. e. FreeCAD, solidworks, G-MESH. Which one goes better with LIGGGHTS?
How do i know if my mesh is good enough or not? Thank you inadvance for your expertise.
Best regards,
ZYan

Hi,

Hi,

I have been trying to simulate particle flow through what is basically a rock impeller, which runs at approximately 1800 rpm. Particle speeds can be up to around 60 m/s, and maybe 40% of particles will fly through both the impeller walls and the outer (static) wall. Both are generated from stl files.

I have tried reducing the timestep down to 1e-7, with no noticeable improvement, and have also tried reducing the mesh spacing in the stl files.

Is there anything else I can do to improve the detection rate?

I have been trying to add a new plasticity contact model to the LIGGGHTS code. I have the formulation down but this model requires I keep track of the plastic deformation between particle-particle and particle-wall contacts. It should work similarly to the shearing array that is present in the code. However, I have been unable to add the array properly.

Hi everyone

I have written a small piece of code that converts the dump file to vtk. It works through cmd/comsole in windows and takes the standard fields in dump file i.e. id type type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius. A recompilation after modifying the source code can be done if the field are different than specified.