LIGGGHTS® - User Forum

Hello Everyone,

I am trying to find out the segregation intensity defined by Danckwerts http://link.springer.com/article/10.1007/BF03184936
The key idea is to divide the 3d-region into grids and calculate the number of particles in each cells. Is there a function pre-existing in liggghts or paraview that could aid in the implementation?

Siddharth

I've tried searching the forums and looking that the tutorial cases, and I can't seem to figure out what I'm doing wrong. I'm trying to simulate a very simple case of particles flowing over a heated cylinder (LIGGGHTS 3.1.0). However, it seems that no matter what order I put the fix commands it, I can't actually get the particles to heat up. Can someone look at my code and see if there's something wrong?

Hello,

I found from the compute_pair_gran for wall-particle interaction CONTACT AREA is calculated as A=pi(r^2 - rsq);
While most of the research papers, calculate the maximum contact area(S) as:
S=1.36 k^(2/5) rho^(2/5) D^2 v_i^(4/5);
k is 1/Y_eff;

When I tried to compare my maximum contact area with LIGGGHTS, its not the same. Can any one help me?
Thank you.

I am having a problem with the move/mesh linear/variable style.

Here is the section of my input script:

variable rotator equal .20324
variable liny equal .26
variable linz equal .03

fix lin1 all move/mesh mesh lip linear/variable 0 v_liny v_linz
fix lin2 all move/mesh mesh bucket linear/variable 0 liny linz
fix rot1 all move/mesh mesh lip rotate/variable origin 0 .21656 .36962 axis 1 0 0 omega v_rotator
fix rot2 all move/mesh mesh bucket rotate/variable origin 0 .21656 .36962 axis 1 0 0 omega v_rotator

Hi,

If possible can anyone provide the reference of hertz time provided in the LIGGGHTS manual?

dt_h = 2.87*(m_eff^2/(r_eff*Y_eff^2*v_max))^0.2.

Thank you.

Hello everyone! i tryed to use this command (you could see it below) to initiate simulation with parallel computing
The manual says that i should use this command
mpirun -np 8 liggghts -in in.script
i used for the chute_wear example
mpirun -np 8 liggghts -in in.chute_wear

But is doesn't work properly, i mean, it uses only one processor and the log says:
1 by 1 by 1 MPI processor grid
Loop time of 115.306 on 1 procs for 99999 steps with 834 atoms

Hi,

I'm looking for an open source / free DEM software for simulating the packaging process of a packed bed reactor. I need to calculate the voidage fraction of the resulting packed bed.

The bed consists of spherical and cylindrical particles of different sizes. I could not find this information in the documentation so I'm going to ask here: Is liggghts capable of running a simulation similar to this video: https://www.youtube.com/watch?v=C3uTXLfkY-Q

Hello Liggghts Team,

i am currently writing my thesis about analyzing the homogeneity of Packings created with LIGGGHTS and need to know which particle placement algorithm is implemented in the program.
It seems to be a Random Sequential Addition algorithm, but i don't know how it works exactly/if it uses any special implementations of RSA.
I tried studying the Sourcecode, but it's much to complex for someone with my limited programming experience :-).

Hello guys,

I want to loop every particle at the end of every time-step,then do some calculations about the arrays, reserve the values and return the values. So if I want to achieve this, what should I do?

Best regards,

LEO

Hi,

While setting up a case for a CFDEM simulation, we encountered a problem with the perceived packing density.

We first inserted the particles mid-air and let them settle. The bed height after settling was much higher than in reality, which is why we tried a higher gravity as well as shrinking the particles and cycling between growing and relaxing, to no avail.

Has anyone had a similar issue before? We would appreciate any response.