LIGGGHTS® - User Forum

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

Creating atoms after restart files

Submitted by SHUBHAM AGARWAL on Wed, 07/07/2021 - 00:29

Hi
I am using LIGGGHTS-flexible fiber version
I have a step-wise simulation process for which I create several restart files. Later in the simulation, I need to create some atoms, However, I am not able to do that as LIGGGHTS does not allow it.
Is there a way to get around this issue?

Thanks
Shubham

USING HYBRID/OVERLAY

Submitted by mehryar on Thu, 07/01/2021 - 05:30

Hello everyone!

I want to use hybrid/overlay, and I don't know how to use gran models. When I use:

pair_style hybrid/overlay gran model hertz tangential history

I got:
pair_style hybrid/overlay gran model hertz tangential history colloid 1.54e-4 yukawa/colloid 1.0408e6 1.54e-4
ERROR on proc 0: unknown contact model (.../CFDEM/LIGGGHTS/src/pair_gran_proxy.cpp:82)

Did anyone experience this error in using hybrid/overlay? and how to fix this!

Thanks!

update on run end flag

Submitted by jagan1mohan on Mon, 06/28/2021 - 15:06

Hello Team, I'm building a script and due to some strange reason, error message suggests me to use update_on_run_end yes flag in compute(s). For example,

variable vY atom mass*vy*vy
compute vYSum all reduce update_on_run_end yes sum v_vY

Let us say I've to simulate 1000000 time-steps, I can do it either in one go (Method: 1) or break 1000000 into two parts in which second part is started using read_restart from first part (Method: 2). My observation is that, everything else remaining absolutely same, the results are very very different from Method 1 and Method 2.

Two computers - same liggghts version, same openMPI, SIGNIFICANTLY different results

Submitted by pfalkingham on Mon, 06/21/2021 - 11:07

Hello,

*This is a new version of an edited post because I originally thought this was a liggghts versioning issue, but it certainly isn't.*

I'm using this input data: https://1drv.ms/u/s!Am5GkbZS_98Xto1HN3LSdxzKI-x0fw?e=RBzhV9

Vibrating screen with varying stroke along the deck

Submitted by Mishal on Sat, 06/19/2021 - 12:31

Hi Guys

I am new to LIGGGHTS and and DEM analysis, my background is structural engineering and dynamics.
I would like to use LIGGGHTS to study a new type of vibrating screen which I am working on.

Current screens have either a linear, circular or elliptical stroke, with the stoke being constant at all points of the screen.
My proposed screen model will have a stroke which varies on various locations along the deck length.

DEM-SPH COUPLING

Submitted by PABLO PEREZ on Tue, 06/15/2021 - 01:34

Hello everyone, i´m studing of master in mechanical enginner and i very interested in the cpupling between DEM - SPH methods. I´m searching information about this topics and if possible this coupling winth liggghts-public.
Specifically, i´m interested do a simulation about a ball mills with water + solids.
i need know if this is possible do with liggghts-public.
i will be attent to comments.

regards

Insert/stream error

Submitted by abdelmalek.bellal on Mon, 06/14/2021 - 05:37

I spent a lot of time on this error but I could not solve it:
ERROR: Fix insert/stream (id ins): unknown keyword or wrong keyword order (../fix_insert_stream.cpp:151)

This my code:

#region and insertion
group nve_group region reg
fix ins nve_group insert/stream seed 49979687 distributiontemplate pdd1 vol ${alphastart} 200 region inbox

I attached the script, I need also help in defining the possible errors in this code I want to create the model shown in the attached figure

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