LIGGGHTS® - User Forum

LIGGGHTS® related topics can be discussed here: discussion about models, installation, feature requests and general discussion

2D simulations no more?

Submitted by kevin.eipe on Fri, 05/15/2015 - 13:54

Hi everyone,

Firstly, Thank you to Christoph Kloss and team for developing the newest LIGGGHTS PUBLIC upate (LIGGGHTS 3.2.0).

I had a simple query; will 2d simulations no longer be supported?

Fix pour and fix pour legacy have been removed, and they were commands for liggghts 2d particle insertion.

Unless my assumption is wrong, and those aren't the only fix commands for inserting particles in 2d?

Cheers everyone.

Thanks,

Kevin

compute overlap

Submitted by abdulrahmanalharbi on Mon, 05/11/2015 - 14:08

Dear all,

I was trying to understand how the overlap can be measured in LIGGGHTS if we have two spheres in collision. I know that I can find the value of the overlap through this equation (from the positions):
Overlap= d-r ;

But actually I am looking for the original equation that has been used in the source to compute the overlap for any collision.

I would be very grateful if you could provide me with any information (equation or paper or book) about computing the overlap in DEM .

Many thanks,
Abdul

how to model a wire interacting by particles

Submitted by ma on Sun, 05/10/2015 - 08:38

Hi,
I want to model a wire in a spiral scheme (like a wire-reinforced membrane) that encloses some particles. the wire should interact with particles and should be able to deform . If bond atomstyle is applicable here what should I add to the code to effectively simulate the interactions. Is there any example in this case?

Any suggestion will be regarded
mojgan

how to generate a very loose packing

Submitted by ma on Sun, 05/10/2015 - 08:19

Hi
I am trying to generate a very loose packing by radius expansion method. I pack smaller particles randomly and then assign a friction coefficient (i.e 0.24 in my case) and allow the particles to grow up to a desired radius. consequently, the consolidation procedure is modeled. The method does not result in a very loose pack and the void ratio does not differ significantly from that in a specimen with a friction coefficient of 0.0. the code is as follows

limitations in liggghts code

Submitted by ravirasoon1991 on Sun, 05/10/2015 - 00:57

Hello,

Can anyone let me know like what are the limitations/restrictions of LIGGGHTS code?
Like particle size, is this code valid for nano-sized particles also?
I know there is "vol_limit" , is there any specific answer for choosing "vol_limit < 1e-12" ?
If I change to "vol_limit < 1e-20", is the code still valid? or do I need to change any properties?

If possible please let me know the limitations of LIGGGHTS code.

Thank you.

simulation box increasing when using hybrid granular molecular

Submitted by cheng1988sjtu on Thu, 05/07/2015 - 20:34

Hi ,

I tried to use hybrid granular molecular to simulate multisphere systems, the atoms are successfully read, and I used fix rigid infile to define the center of mass, and moments of inertia. Initially, the non-spherical bodies are uniformly distributed in the simulation box, with a volume fraction of about 0.1, and the first few thousand time steps are running fine (time step = 1e-6), however, the simulation box will increasing after several thousand of time steps, and I can see the total amount of atoms are decreasing.

Simulation with read_data slower than without it?

Submitted by carlesbp on Wed, 05/06/2015 - 17:32

Hi all,

I am running a rotating mill with 1 atom, velocities and positions are read from a read_data file. It runs and the behaviour of the atom is as expected, but the time it takes to finish the simulation is way too long, obtaining 0.23 seconds per iteration.

If I keep all the same settings but insert the particle with the insert/stream command, the time is much smaller, such as 0.005 seconds per iteration.

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