LIGGGHTS® - User Forum

Dear all,
I am trying to simulate the free motion of a mesh under the
effect of its interaction with some granular particles.

The idea is to import the .stl mesh with fix mesh/surface/stress,
to compute the forces acting on it and then update its position with
with fix move/mesh rotate/variable and translate/variable styles.

However, I am encountering this error:
"ERROR: Mesh freerotor: The minumum angle of mesh element 6 (line 58) is lower than the specified curvature."

Attached is a little stl-to-vtk conversion tool. From the command line, it is just './convert file.stl', where 'file.stl' can be whatever you want. It should produce a vtk file called 'file.vtk'. Limit of 1e6 facets/vertices in the STL file.

Best regards,
Chris

Hi,
is it possible to create a region from a CAD file?
The "region" command has "mesh/tet" style, this one would be very useful if I could generate a ASCII VTK file as the manual says, but I really don't know how to do it from a CAD or stl file. Does anybody know how to do it?

Regards!

hi everybody,
I am trying to dump pair interactions (both for all particles and those that are placed in a specific region (defined as MSgroup), seperately) via pair/gran/local, when I use two computes for example as
1.compute GranInter MSgroup pair/gran/local pos id force history
2.compute MGranInter all pair/gran/local pos id force history
it says that Pair gran allows only one compute of type pair/local.

Dear Forumers,
I am using Liggghts2.3.2 with its function to calculate solid flux using command "fix massflow/mesh". However, I could not dump/output the flux. I try to wirte its four components using "variables" along with "fix print" command but failed. May be I am not familiar with the function of writing out data of Liggghts. Could any one give me some suggestions? Thanks in advance.

Dear Forumers:
I noticed a new feature form the announcement of the LIGGGHTS2.3 release, which can calculate solid resident time distribution in a region- "Added new fix property/atom/tracer and fix property/atom/tracer/stream commands along with a new compute nparticles/tracer/region command for the calculation of residence time distributions". Howerer, I can not find a test case or a tutorial to use this feature, and I also wonder how to ouptut the results as simulation processes. If anybody knows, please give me some clue. Thanks in advance.

Hello,

I am discovering a very interesting function "mesh/surface/stress/servo" which enables to apply a force on a wall.

fix servo all mesh/surface/stress/servo file plate.stl type 1 com 0. 0. 0. ctrlPV force dim z set_point -10 vel_max 1.

First, I would like to know, what is the parameter 'set_point' in your example ?

Then, I would like to apply a force (10N) on two walls (top and bottom) to perform a compression test in the Z-direction.

Hello all,

I'm interested in simulating a horizontally rotating bin where particles leave through an orifice geometry that I have designed.

Hi all

I've been reading the manual in order know how to speed up the simulation. If I increase the number of processors to running the simulation I'll be able to reduce the pair time. is it the best solution to achieve my aim?
Can anybody tell me the steps that I have to follow?

best.

I'm having a frustrating issue at the moment. I set up a simulation (at the moment with basically no particles), and then import an ascii stl mesh (produced in meshlab) with the following line:

fix MT all mesh/surface file MT.stl type 1 rotate axis -3.832567 0.000000 2.832567 angle 17.365650

When I look at the output, the mesh has rotated, but it has also become larger. Am I doing something wrong here, or is this a bug?

tar attached containing full input script and original stl mesh.