LIGGGHTS® - User Forum

Hi,

I am wondering if developers are on their way to implementing SJKR forces on superquadric particles.

This would be really useful for some of my simulations.

Best regards,

Oier.

Hi
In my simulation, I am using three types of atoms (say 1,2,3) I need to define the contact stiffness between each of them (E1,E2, E3)
For that I am using the following
fix m1 all property/global youngsModulus peratomtype ${E1} ${E2} ${E3}

As far as I can understand, this command has assigned a young modulus to each of the particles. How it takes care say when atom 1 and 3 come in contact. Is there a way to assign contact modulus like that? I tried peratomtypepair but it did not work.

Thanks
Shubham

Hi
I am using LIGGGHTS - flexible fibers version
I am defining a prism region using the following command:
variable dummy2 equal 1.01*${beam_length}

region bc_blade prism ${dummy2} ${dummy2}+${blade_particle_diameter} -${blade_particle_radius} ${blade_particle_radius} 0 ${blade_length} 0 0 ${blade_particle_radius} units box

All the variable are defined tin the code, however I am encountering the following error;
Illegal region prism command

How it can be solved??

Hi
I would like to count the collision frequency between different types of particles in each time step.
i have 16 types of particles :
i did manage to count for each type, but what i need is to count for example :
Between Type 1 and Type 1, between Type 1 and Type 2 ...., between Type 16 and Type 16.
here is my code :

Hello everyone,

I was wondering about one of the implementation details of liquid bridge models, namely the definition of the minimum separation distance ratio, which is required to have values > 1 and is recommended to have a value of around 1.01 according to the documentation

I am creating rigid bodies from groups of spheres using, for example,

fix 1 all rigid molecule

From doing some simple tests with two spheres setup as a diatomic molecule, it appears that LIGGGHTS will always output the total energy - translational + rotational - for ke. I want to separate this energy into rotational and translational pieces in the thermo output. LAMMPS seems to have had ways to do this with compute temp, but that does not appear to be a thing in LIGGGHTS. I tried using erotate, but that does not seem to correlate with what I need at all.

Hello
I am currently using LIGGGGHTS-flexible fibers version for granular bonds.
In my simulation I have 2 groups (web & blade), and I want to calculate the force that web exerts on the blade. For that I tried the following command:
compute force_inter blade group/group web

However, I am encountering the error saying that "Pair style does not support group/group".
In the contact style, I am using the following:
"pair_style gran model hertz tangential history "

Can someone please help me to resolve this

Thanks

I would like to count the overall number of collisions between different types of particles.

Suppose we have 3 types of particles

So what i need is the total number of collisions between each type, between type 1 and type 2 , between type 1 and type 3, and between type 2 and type 3, Is there a way to do this?

Do i have to make some changes in the source code of liggghts or use a predefined liggghts command .

Ps: i have 20 different type of particles.

Hi,

I'm looking to calculate the dissipated energy for colliding spheres. In the documentation, the computeDissipatedEnergy option for a granular model references a fix style to use later that throws up an error when I tried to use it - so I am unable to access these values. In a previous forum post I read it seems that this is a premium feature (I am only using the public version). My question is, is there a way in LIGGGHTS-public to efficiently track the energy dissipation?

Hello !

I've been using LIGGGHTS for around a year now mainly with spherical particles. I want to create a '2D' model using cylindrical particles, it would be a 3D plan symmetrical model. To do so I created superquadric particles with N1=8 and N2=2. But whenever I try to use the command 'write_data' to save state the program crashes. I get the following error :