LIGGGHTS® - User Forum

I want to simulate a particle inlet boundary with given solid volume fraction and velocity, i.e the solid volume fraction and velocity in this boudary region is always fixed. I defined a region above the boundary, calculated the massrate, and used the insert/rate/region command. Since I want to keep the solid volume fraction fixed, should I set the insert_every to be 1?
I found many warnings come out.

Hi everyone,

I need to make a fluid-particle simulation but I can't use CFD for the fluid because of the length scale of my particles interactions. According to this, i'm looking to make a mesoscale coupling between SPH and DEM. I know that LIGGGHTS has both models but is it possible to couple them?

Thanks in advance.

Dear all,

i'm simulating granular particles flowing through a pipe. Does LIGGGHTS provide a method to count particle-particle collisions per timestep?

Best Regards
Felix

I am just wondering that is there any way to automatically adjust the timestep in the simulation based on the size of newly generated/inserted particles. One such way is to use fix dt/reset but in that the impornat keyword is XMAX which seems difficult to produce.

Hi,

when I am trying to use the compute inertia/molecule on a molecule defined by fix rigid, I receive an error message like:
"ERROR: Invalid compute style (modify.cpp:883)"

I compiled LIGGGHTS together with the MOLECULE package and I am wondering why this would be an invalid compute style?

My files are attached to this post.

Best regards,
MiRa

Hi Colleagues,
I have problems with the .stl geometry rencently. I used SolidWorks to create
3D geometric models and then save them in .stl format as the mesh walls. However,
when I viewed the geometry with Paraview, they looked like solid. I noitced in the tutorial examples, all the geomery are surface mesh (please see the attached figures). the example.png is from the tutorial example, and the myexample.png shows my own example.

I failed to save plane/surface in the solidwork as .stl.

Hello,

I'm thinking about how to choose the optimal time increment for my simulations. I set up a very simple testcase in order to study the behaviour of contact interaction between particles and STL-geometries, defined as wall.
Video: http://www.youtube.com/watch?v=IBf3vUwHh-w
First, I calculated the timestep as provided by many posts in this forum with the formula dt = 0.2*dt_rayleigh:
r = 0.005
rho = 8000
Y = 5e6
nu = 0.3
G = Y/(2*(1+nu)) = 1923076.92

Hello,

Hi all,

I am trying to do simulation on a rotary drum, simulating the rotation by changing the gravity force. I hope you could help me. Here is my code:

atom_style granular
atom_modify map array
boundary p p p
echo screen
newton off

units si

communicate single vel yes

region reg block 0 2.4 0 0.314 0 0.314 units box
create_box 1 reg

neighbor 0.02 bin
neigh_modify delay 0

Hi,

I define a wall with the stl style, and I want to change the normal direction of this wall. Can anyone tell me how to do it ?

Thanks