LIGGGHTS® - User Forum

Hi Everyone,

I am looking for a way to use the timestep as if it is equal to 1/40 of the contact time (given stiffness and viscosity it should be possible to obtain the contact time).
Is there a built in function or should I compute it via variable?

Greetings
Luca

Hi, I'm running the simulation of steel particle sedimentation.
In the input file of LIGGGHTS, I think that the unit of 'YoungsModulus' is [Pa] in SI unit.
But, when I write the steel's mechanical property(about 200GPa = 200.e9) on particle and aluminium property (about 68.9GPa= 689.e8) on the wall,
the calculation results is so weird. (The particle's rebounded force is very large...)
I want to know the definite unit of YoungsModulus in the input file.
Thank you

bc

In fix_mesh_surface_stress.cpp line 295 of LIGGGHTS 3.0.0, it writes:
E *= 2.*k_finnie_[atomTypeWall()-1][atom->type[ip]-1] * v_rel_mag * vectorMag3D(frc);
As defined in finnie wear document, E is a time derivative of the dimensionless mass. E should be accumulate with time.
However, I can't find any usage of timestep in fix_mesh_surface_stress.cpp.
So should I multiple the output data of "wear" in dump file by timestep to get the erosion depth?

Hello, A few days ago i asked how to count particles using the vec_side keyword using a planar surface. The problem is that now i have to count particles in other section of the mill, but with a non planar surface. For this, i am using the point_at_outlet keyword, but i really don't know how to set it to works fine. I will add the files in order to give me some advices.

Best regards

Nicolás.

Hello every one,

I am trying to modify the code which was written for heat/gran/conduction to change some parameters.

I was able to find the code for the second term for heat conduction equation ( heat transfer coefficient, particles temperature), but I was not able to find the source and header files in which the first term of heat conduction was written (time step, change of temperature with change of time step, specific thermal conductivity and particle mass ).

Hi everyone!
I'm new in LIGGGHTS and to begin I see the example chute_wear, in this , I have a question, how i can get the contact force between the chute and the particles?

With pressure and area I can calculate force per cell, but it's a scalar value, and I would like to sum all of this to get a resultant force on the chute per time step.
I've done this ( like the graph), but are in different directions, thath is wrong :(

Hi.

I have a problem with inserting a wall in my simulation.
When I launch the simulation, the one spherical particle I insert, falls down to infinity, ignoring the wall.

Can anyone take a look

## code is attached

Greetings,
Luca

Submitted by Noel682 on Fri, 10/16/2015 - 17:09

Hi all... developers and users,

I am very new to LIGGGHTS and I have a question about an exercise:

# Using: LIGGGHTS (Version LIGGGHTS-PUBLIC 3.2.1)

Hi all... developers and users,

I am very new to LIGGGHTS and I have a question about an exercise:

# Using: LIGGGHTS (Version LIGGGHTS-PUBLIC 3.2.1)

Hello everybody:

I downloaded the most recent LIGGGHTS version to simulate multisphere in the inside of a mill. However, when i compile it, these warnings appear:

WARNING: time step too large or skin too small - particles may travel a distance of 3.440580 per time-step, but half skin is 0.025000
WARNING: time step way too large - particles move further than the minimum radius in one step

My question is how to fix those warnings in order to have a better simulation?.