Wet Granular Flow

Submitted by Jai on Wed, 07/06/2011 - 14:27

I am pretty new to LIGGGHTS and DEM simulations. I am trying to model granular flow of particles with cohesion force between them. The flow should be like - they start from a point and gather mass progressively in a fan‐like shape as they slide down the slope with some wet/slurry effect between the particles along with cohesion force. I have started looking at the chute wear example by altering the Hertz cohesion coefficient to 1 to have cohesion effect between the particles.

Has anyone done any such kind of simulation using LIGGGHTs before?

Can any one please help me on how to model this kind of simulation. What LAMMPS/LIGGGHTs commands I should be considering? Also I am looking to change the length and the angle of the chute in the chute wear example. Is it possible to achieve it.

Regards

Jai

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ckloss's picture

ckloss | Wed, 07/06/2011 - 15:02

Hi Jay,

>>Hertz cohesion coefficient to 1
don't know what you refer to by this? There is a cohesion model, based on a "cohesion energy density". Have a look the the "cohesion" tutorial case

>>with some wet/slurry effect
If the particles are just a bit wet, you will probably be fine with a cohesion model. If you have a low Re flow slurry without much fluid dynamics going on you can try if maybe fix viscous helps to picture what you want. If you have a real two phase system, you will need a coupled CFD-DEM simulation

>>Also I am looking to change the length and the angle of the chute in the chute wear example.
>>Is it possible to achieve it.
You can scale and rotate the geometry, see doc for fix mesh/gran

Cheers,
Christoph

Jai | Thu, 07/07/2011 - 11:14

Hi Christoph,

Thanks for your reply. The particles are just a bit wet and not much of fluid dynamics involved. I will give a try with fix viscous and see how it looks like.

Is it possible to make the granular particles (say 1000 particles) with little internal cohesion among individual particles flow from a start point on an inclined plane and gather more and more particles(mass) progressively as they slide down the slope forming a a fan-like shape.

This simulation is very much common in continuum model but is it possible to make the granular particles flow that way? What properties/commands of LIGGGHTs I should be looking at for such a kind of simulation?

Regards

Jai

ckloss's picture

ckloss | Thu, 07/07/2011 - 11:20

>>Is it possible to make the granular particles (say 1000 particles) with little internal cohesion
>>among individual particles flow from a start point on an inclined plane and gather more and
>>more particles(mass) progressively as they slide down the slope forming a a fan-like shape
I guess this will be your task to find that out... :-)

>>What properties/commands of LIGGGHTs I should be looking at for such a kind of simulation?
As I said, have a look at the cohesion tutorial

Cheers,
Christoph

Jai | Fri, 07/08/2011 - 10:37

Hi Christoph,

Is it possible to create a new pour style for this kind of pour? I was looking at the random_park.cpp and fix_pour_dev.cpp files. Can I add a new function in the random_park.cpp file for this new pour style and call it from fix_pour_dev.cpp to achieve this new pour style that I am trying to simulate?

Any other files to look at, please let me know.

Thanks!

Jai

ckloss's picture

ckloss | Fri, 07/08/2011 - 11:13

Have a look at the newer insertion commands (fix_insert*). Fix pour/dev will be deprecated at some point.

Cheers,
Christoph

Jai | Fri, 07/08/2011 - 16:53

Hi Christoph,
When I try to run the insert_stream example I get the below error message. I am using

ERROR: Unknown command: fix ins nve_group insert/stream seed 100001 distributiontemplate pdd1 nparticles 5000 vel constant 0. -0.5 -2. particlerate 1000
overlapcheck yes insertion_face ins_mesh extrude_length 0.6

I am using the iggghts_1p3p1 version. Is there any special package I need to load for this fix style? Also can you please point me to the manual entry for fix insert, insert/stream and insert/pack commands, I couldn't find one :-(

Thanks!
Jai

ckloss's picture

ckloss | Fri, 07/08/2011 - 17:22

>>Is there any special package I need to load for this fix style?
No, try make clean-all and then rebuild LIGGGHTS

>>Also can you please point me to the manual entry
There is no manual yet, but the command is pretty self-explanatory i think
Also, you can have a look at the source code

Christoph

Jai | Fri, 07/08/2011 - 18:35

Hi Christoph,
I did make clean-all and rebuild LIGGGHTs, but still getting the same error message.

Jai | Fri, 07/08/2011 - 19:45

Hi Christoph,
I am using the version liggghts_1p3p1 that I downloaded from the liggghts website. I didnt know how to use git repository, so I didnt get it from there.

I ran the fix insert/pack example and there are no issues with it. only problem is with fix insert/stream.

Jai

ckloss's picture

ckloss | Mon, 07/11/2011 - 11:01

Is there a fix_insert_stream.h/cpp in your src directory?

Jai | Tue, 07/12/2011 - 12:34

Hi Christoph,
Yes I have the cpp and .h files in my src directory. I rebuilt liggghts and it is working now. Thanks for your help.