CFDEM®coupling - User Forum

Hi Chris,

I found in the release history that

+ new functionality to allow adding forces only to DEM integration (not to momentum exchange terms)

May I ask how to implement this?
I guess to use the variable DEMForces.

So I can give a value to both of DEMForces and impForces.
Then DEMForces+impForces will be applied to DEM and impForces will be used in fluid phase.

Please let me know if I'm wrong.

Thank you in advance.

rq

hello cfdemers,

some questions arise when I use the cfdem, hope you can give me some suggestions.

#question on pressure drop
As we know, change of pressure drop with inlet velocity is used to test the minimum fluidized velocity when justify whether the simulation is correct.
So I take a test using probe and pressureDrop function in controldict.
the simulation parameters are:
volume:60mm*60mm*600, x y z
grid:8*8*60, x y z
particle diameter:4mm
particle number:15660
particle density:2700kg/m^3
minimum fluidized velocity:1.77m/s

and two probe locations are used:

Dear CFDEMers

Starting from the settlingTestMPI I build up a case with 729 particles with diam 0.001 in a 0.1x0.01x0.01 simulation box. On the left side of the box there is an Inlet with vmean=1 and on the right side an outlet with p=0. For the box and the particles the Re is <1 which implies the flow is laminar. Running liggghts and OpenFOAM separately there are no problems. I checked the timestep in liggghts with fix check/timestep/gran.

Hi Chris,

I found the virtual mass model will crash if the number of the particles are greater than 64.

I locate the line of crash is at line 118:
UrelOld_[index][j] = Ur[j];

Do you have any idea?

Thanks.

rq

Hi Chris,

I think the dummy density bug is still in the solver code, i.e.

Line 81 of cfdemSolverPiso.C should be

Ksl.internalField() = particleCloud.momCoupleM(0).impMomSource()/rho;

Please check it.

Thanks.

rq

Hi,

I want to implement a simulation of viscoelastic flow that consists of a polymer melt with suspensed microscale particles . Does CFDEM have the module for viscoelastic flow?

AC

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.