CFDEM®coupling - User Forum

Hi all

I'd like to work CFD-DEM coupling out. But I can't find useful literature. Does a description on 2-way and 4-way coupling exist (mathematical description)? I found nothing about that on the net. General detailed literature about CFD-DEM i.e. books, (professorial) dissertation? In papers the information is often fragmentary and very short.

Thanks for information.
Claudio

Hi,

I am trying to add an artificial random-walk diffusion model.

It has this form:

xp(t + ∆t ) = xp(t ) + up ∆t + ξ sqrt(2 Ds ∆t)

where Ds is a constant, ξ is a random number from 0 to 1.

Could anyone tell me where I can implement this?
My guess is at LIGGGHTS source code, but I have no idea which file to modify.

Please help me!
Thanks.

rq

Hi

In the paper "An Open Source CFD-DEM Perspective" I've read about the Chimera-Approach. Is this method state of the art in CFDEM or present this paper just a possible prospective feature of CFDEM?
If it is state of the art my next question is: how is the mesh for exchange fields generated and need it some modifications by the user? Need the momentum exchange mesh special attentions by the user? In Liggghts I've never read something about modifying mesh.

Thanks for explanation.
Cheers
Claudio

Hi Chris, Christoph, Alice, and cfdemers,

Encouraged by Chris, I would like to summarize the problems/modification in my happy time with CFDEM.

I am trying to simulate a dense particle-laden jet in still water.
To validate the code, I am trying to reproduce the experiment Case II of

Parthasarathy RN; Faeth GM (1987) Structure of particle-laden turbulent water jets in still water. Int J of Multiphase Flow 13:
699—716

I am using LES model of locDynOneEqEddy.

First, I reproduced single-phase jet. Thanks to OpenFOAM, the simulation looks perfect.

hello all,
i tried to run hopperemptying example of cfdem but it stooped with an error:

anoop@ubuntu:~/OpenFOAM/anoop-2.0.x/run/cfdemSolverPiso_shared/HopperEmptying/DEM$ liggghts < in.liggghts_init
LIGGGHTS 1.4.5 based on lammps-10Mar10
Created orthogonal box = (0 -0.006 -0.08) to (0.3 0 0.5)
ERROR: Bad grid of processors

what does it mean??
i changed processors to * * * but error is still same.
thanks for any further reply.

Anoop

HI,
Plz put swak4foam in direct downloads as im unable to download it via svn or git due to proxy limitations.

thnx

hi all,
Im working on gas-solid fluidized bed simulation. im new on cfdem. i have run the same problm openfoam (euler-euler approach). now im moving towards eulerian-lagrangian method. my problem is that i have seen cfdem example cases and have run settlingtestmpi. for gas-solid fluidized bed i have to pack bed upto some length with solid particles. in openfoam i did this with setfieldsdict but here setfields command is not working.
>> Is funkysetfields command related to this and does the same thing??
>> what is the meaning of voidfractionprev and voidfractionnext??

Dear all

I'm learning CFDEM. I started by analyzing the settling example. Then I modified this case more and more. At the beginning it seemed to work well. Any questions I tried to answer with the LAMMPS documentation and this forum. But now I'm standing in front of a big wall. My main problems are:

1) wall material in DEM: in the documentation i just found that the last number determines the wall material.
e.g.: fix xwalls all wall/gran/hooke 1 0 xplane 0 0.01 1
What kind of wall-types can I use? Where are they specified? How can I modify them?

hello sir,

I am new on liggghts and cfdem. i have installed liggghts and cfdem and its coupling with openfoam as per instructions given on this website. Now i want to simulate liggghts test cases. i made liggghts on ubuntu-10.04 LTS within src directory with these commands:
make clean-all
make fedora_fpic (i omitted -j)
make makelib
make -f Makefile.lib fedora_fpic

by this i found an executable lmp_fedora_fpic and Obj_fedora_fpic folder.

for example case run i entered these commands in terminal:
cd LIGGGHTS/liggghts_GIT/examples/LIGGGHTS/packing

sir,
plz suggest me the proper commands to run settlingtestmpi dem case of cfdem examples. how to convert output data in vtk format with pizza?