CFDEM®coupling - User Forum

Hello guys, need some help.

Currently, I am doing simulation in LIGGGHTS. My particles insertion area and surface have height approximately 0.02 in si units.

I would like to add some random height so that my particles drop from different height in the same simulations. Purpose of this is to bring noise on heights.

So I want to drop particles randomly at the height of 0.02 +- 10 % or 0.02 +- 20 %while running simulation.

Is it possible to add this idea in liggghts script?

What will be the command?

Thank you.

Hi everyone,
did anyone do a simulation with cfdemSolverIB and high viscosity values? When I use viscosity values like 10 for moderate Reynolds numbers, the code does not converge and even the Glowinski problem does not give a proper result. So can you please give me some hints concerning this issue?
Cheers,
Mohammad

Hi All,

I am a beginner of CFDEM. It seems like we need to create an Allrun.sh script file to run to a simulation. But I could not find any documents or tutorials about writing this Allrun script. I have looked the code in Allrun files in many tutorials, and they all have some differences. So it makes it hard for me to understand and modify those Allrun files for my own simulations. Hope you can help with it.

Thanks and Regards,

Dear all,

When I get started to run those examples in tutorals, I always get following errors:

CFDEMcoupling version: cfdem-3.8.1
, compatible to LIGGGHTS version: 3.8.0
, compatible to OF version and build: 5.x-commit-538044ac05c4672b37c7df607dca1116fa88df88

You are currently using:
OF version: 5.0
OF build: 5.0
CFDEM build:

Dear all
I am using CFDEM to study the seepage in sand, and I want to use the ratio between the fluid velocity and the particle velocity to distinguish different particle groups, how can i do to achieve that? It seems that the there is no exsist liggghts command which can be used to access the fluid velocity directly?
Zhang Peiyun

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

Hello everyone!! I am new to DEM and CFD. I have been using LIGGGHTS for past few months. I want to model the melting and solidification of powder bed as in Selective Laser Melting(SLM) or Laser Powder Bed Fusion(LPBF). From the papers which I have read, I came to know that it can be done using CFDEM coupling. I started just with LIGGGHTS and have been able to model the powder bed. Now I want to move forward with melting and solidification. Any help in this direction would be much appreciated as I am running out of time.

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.

Hello all,
I work on shear fault and I would like to use LIGGGHTS to simulate it. Files (.stl and in.) are in the attachments.
Currently top and bottom plates are smooth but I would like to have rough one.
I would like to glue particles with those plate before shearing.
I have downloaded LIGGGHTS_Flexible_Fibers version and I would like to know if it is possible to glue particles and mesh. And if it is possible how.
I stay available
Regards

Alexandre Sac--Morane

Hello LIGGGHTS forum, I am trying to run a simulation in an inclined surface. Till now my script is working nicely.
I want to add viscous and damp command in my script.

When ever I added it as ` fix 1 viscous 0.1 ` or `fix 1 damp viscous 0.5 scale 3 2.5` I got following message.
```
ERROR: Could not find fix group ID

```

I also tried to add as `fix m6 viscous...` got the same error.

How do I add them correctly?

Any help would be appreciated.

Thanks a lot.

My script

```

# Initialize