LIGGGHTS® - User Forum

Hello everyone!

I'm working on a simulation and I could really use some help. I want to simulate the flow of granular material in the space between two concentric cylinders. The inner cylinder is rotating and therefore causes the material to move. It's something like a rheometer but with granules instead of fluid.

I am trying to simulate the superquadric particles but after few time steps the code stops and a following error pops up.
ERROR on proc 0: Using default surface model for non-spherical particles! (../surface_model_default.h:144)

the model I am using is pair_style gran model hertz tangential history surface superquadric.

Does anyone have the same problem or knows the cause of the error?

Hi, recently I was using LIGGGHTS with 2 meshes but it just stopped without any error message.

The line I used for importing mesh is below.

fix cydmesh all mesh/surface file meshes/62_Container_hexa_E_10.stl type 2 verbose yes scale 0.002
fix obstacle all mesh/surface/stress file meshes/obstacle_deg_0.stl type 2 verbose yes scale 0.002
fix cwall all wall/gran model hertz tangential history mesh n_meshes 2 meshes cydmesh obstacle

I need to make one thing clear about particle insertion in rotating drum.

I have two different simulations with mixed particles.

Simulation one: particles radius 0.04 and radius 0.035

Simulation two : particles radius 0.04 and radius 0.025

I am inserting particles volume wise like 20 % 0.04 and 80 % another one in both simulations.

I realized that number of inserted particles with 0.04 in simulation one is more than number of inserted particles with 0.04 in simulation two (huge difference).

Hi

I want to explicitly measure the mass of two different particles going through a face.

Hello,

We are a very small french research team. And we plane to study the processus of additive manufacturing. The first step is to model the flow of particles on the system. We encounter a few difficulties to understand the behaviour of the software, the underlying physics and we would like to found a easy step by step tutorial and caracteristics examples.

Could you give us some advices to find such sort of documentations and code examples?

Thanks so much,

Sébastien Nadler
R&D projects Leader, Astek society, France

Hello

Hello community!

I am currently working on a test-case script for my Master Thesis. After a while, I started to get along well with case inputs and setups, and that's not a big deal.

At the moment, my biggest challenge is the calculation of the Lacey Index and the approach to calculation. The principle of calculating the mixing index is clear, how to approach the problem and how to start post-processing is quite difficult for me.

Hello,

I am doing rotating drums simulation. For my research, i don't need to include particles filling position. What I need is data from particles adjustment to end.

I know It can be done in preprocessing after simulation however repeated particles id makes is little bit complex. Further, manual process can loose particles information.

I am wondering whether there is such steps in liggghts so that I could ignore particles filling positions in dump file.

Thank you

Hi,

I am running screw-conveyor LIGGGHTS simulations on our University cluster and everything was fine the first week. But now I am running into this error (shown below and attached). The log file has no errors and the same input file runs fine in another Linux system. Can anyone help me figure out what the issue is? Thank you in Advance.

ERROR: In /build/vtk6-9ueea8/vtk6-6.3.0+dfsg2/IO/Legacy/vtkDataWriter.cxx, line 163
vtkRectilinearGridWriter (0x555bb7c3b9a0): Unable to open file: post/pellets_boundingBox_295000.vtk