CFDEM®coupling - User Forum

This is a forum dedicated to CFDEM®coupling using the LIGGGHTS® DEM code and OpenSource CFD.

Particle rotation when using cohesion

Submitted by JohLoh on Mon, 11/20/2017 - 12:40

Hallo everybody.

I have a question about the rotation of cohesive particles when using CFDEM coupling. The particles start to rotate when they overlap with another particle or a wall. If I'm not using CFDEM coupling (only DEM), they don't rotate (see rotate.png). I don't use any rolling friction model. Can someone explain me this behaviour?

many thanks in advance.

Johannes

How to monitor the permeability of the particle specimen?

Submitted by Rachel on Mon, 11/20/2017 - 04:21

Dear all,

I am wondering whether we have a method about monitoring the permeability of the particles specimen. As far as I know, we can monitor the quantity of flow in the outlet boundary to calculate the permeability of the specimen manually. However, I haven't found a command about outputing the quantity of outflow. Could someone tell me which command should I use? or is there any possibility that we output the permeability of the specimen directly?

Thanks you very much!
Regards,
Rachel

Interaction between stl mesh wall in DEM and water in CFD

Submitted by Rachel on Tue, 11/14/2017 - 20:19

Dear all,

When I applied cfdemPisoSolver in my simulation, I found there is no interaction between stl mesh wall in liggghts part and water in openFoam part. Now, I am wondering whether there exist a method to define the contact betwwen water and walls?

In other words, if I want to simulation a similar problem about the drop process of a container full of water, how to define the interaction between water and the container? Is there any method? Any suggersions or clues are appreciated!

Best regards,
Rachel

About the atoms size in LIGGGHTS and the mesh size in OpenFOAM

Submitted by Rachel on Sat, 11/11/2017 - 08:55

Dear all,

I want to ask a question. As I see in this forum, the mesh size of OpenFOAM should be 3-4 times of the particles diameter. If I have some kinds of particles with different diameters such as 1mm, 0.5mm, 0.1mm. Should my mesh size be 3-4 times of the diameters of the larger particles or the smaller particles? Thank you very much.

Besr regards,
Rachel

questions about f_dragforce

Submitted by nan on Wed, 11/08/2017 - 11:25

Dear all,

I am using Model A with following code lines, where implicit method is used. For the fluid force on a particle (Fpf), there are mainly three kinds of components, fd, f_pg (pressure gradient force), f_v (viscous force).

1) what is the true meaning of f_dragforce, does it only referee to the pressure gradient force f_pg + viscous force f_v, namely (Fpf-fd) ?

2) If f_cfd2 is the sum of Fpf for all particles, why I find f_cfd2 < sum (f_dragfroce) << pressure drop * area? The case with cylindrical bed is used.

Small CouplingInterval blows up CFDEM simulation

Submitted by AndresMM on Wed, 11/08/2017 - 08:55

Hi everyone,

I am simulating the pressure drop caused by a compressed bed of packed particles. On the DEM-side I mechanically compressed particles with a moving mesh. I then used this state to create the restart data where I changed the STL for a wall. On the CFDEM-side I apply a velocity of 0.001 in the inlet. I am using cfdemSolverPiso.

About CFDEM tutorial

Submitted by Aries_CFDEM001 on Tue, 11/07/2017 - 15:28

hello
I just installed the CFDEM according to the website but I have no idea where can I get the guide about how to run this simulation especially the post procession. I only got some pic and I want to see the result on the Paraview , so I'd like to know how to use it. videos pdf URLs anything is fine
Thanks

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