LIGGGHTS® - User Forum

I'm trying to model some particles flowing over a heated surface. In my lab, I know how much power my heater consumes, and therefore know the wall heat flux.

Is it possible to apply this boundary condition to a wall in LIGGGHTS? I know how to give a wall a certain temperature, but as stated, I don't technically know that. If this is possible, does the wall have to be an imported mesh, or can it be a primitive? I see that I can compute the heat flux of a particle in contact with a wall, so I thought that making this a fixed value would be easy to do.

Hello everybody!

I was wondering if the order of the material properties fix and the contact model in the LIGGGHTS script matters? In the doc it is not written that the material-fix has to be specified before the pair style command, but I wanted to make sure I can change the script like this and the result will be the same:

Dear LIGGGHTS team,
I'd like to do a simulation which hybrid the granular and sph atom styles
some granular particles in the bottom of a container, then add some water(sph model) on these particles, then close the lid.
My code is as follows

#### initialization #
#variables
variable mass universe 0.001 #0.001
variable h universe 0.012 #0.012

variable lat equal $h/1.2 # = 0.01
variable lathalf equal ${lat}*0.5
variable skin equal $h*0.25
variable wallpos equal ${lathalf}
variable eta equal 0.01*$h*$h

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