LIGGGHTS® - User Forum

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

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

ADFORCE

Submitted by Kashminder on Sat, 06/12/2021 - 00:06

I am trying to use a adforce command to apply a stoke's drag force on a single particle using the following syntax

atom_style granular
atom_modify map array
communicate single vel yes

boundary f f f
newton off
units si
#region reg sphere 0.1 0.1 0.1 0.4 side out
#region reg block -0.05 0.05 -0.05 0.05 0. 0.15 units box
#create_box 1 reg
region reg block -0.005 0.005 -0.005 0.005 0.000 0.002 units box

read_data velo

#processors 2 2 1

Compute used in variable between runs is not current

Submitted by Kashminder on Wed, 06/02/2021 - 19:56

I am using compute like this

compute kash all property/atom z

compute kashi all property/atom x

compute kish all property/atom y

variable b equal c_kash[1]

variable p equal c_kashi[1] #r

And I am getting an error "Compute used in variable between runs is not current. Use the update_on_run_end option for computes to avoid this". I want to Know how and where to use the update_on_run_end option. in Variable command or in compute command above variable.

Time dependent move rotate

Submitted by jagan1mohan on Wed, 06/02/2021 - 17:00

Hello All, I have a question on fix move rotate command in LIGGGHTS. Setup has a drum made up of particles, closely placed so that there is no gap.

I'm first using
fix wall particleWall freeze to freeze particles and then using
fix particleWallRotate particleWall move rotate 0.0 0.0 0.0 0.0 0.0 1.0 0.05 to rotate wall with a constant period of 0.05 sec.
This is working okay.

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