CFDEM®coupling - User Forum

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

mesh refinement

Submitted by mikekaff on Mon, 02/08/2016 - 11:59

Hello to everyone.
I have been trying to modify the twoSpheresGlowinski tutorial from CFDEM in order to simulate a coupled flow (sedimentation) of particles (~400μm diameter) into a non Newtonian fluid.
My main problem seams to be that no cells are selected to be refined and Courant number increases as the steps progress.
These is the log output of the 7th step where it cruses.

Selected 0 cells for refinement out of 8000.
Selected 0 split points out of a possible 0.
Courant Number mean: 1.78356e+41 max: 2.46448e+43

What do I have to change???

KochHillDrag model: how to set-up scaleDrag coeff

Submitted by gabrieleDOF on Fri, 02/05/2016 - 20:03

Dear all,

I have some doubt about how to set the "KochHillDrag" model.
My case treats a cloud of solid particles that flows through a high viscosity liquid.
I found that the simulation blows up due to the drag force values, which arise almost immediately.
On the other side I found that, setting the "scaleDrag" parameter to a value much lower than 1 (between 0.3 and 0.5),
the simulation becomes stable and runs well.

CFDEM coupling memory requirements

Submitted by mohsen_ba65 on Mon, 02/01/2016 - 21:53

Hi,

I am running into memory issues running cfdem on a cluster. I wanted to know if there is a way to estimate memory requirement of a simulation.

My current case is an 18" sphere with one inlet on side and one outlet on top. I was wandering if the size of the sphere could influence the memory requirements of the simulation and if yes then how. Is there any method to find an estimate of memory requirements?
If my simulation asks for more memory than what is defined on the cluster then it will crash and stop.

Thanks,
Mohsen

CFDEMsolverIB FOAM fatal error

Submitted by bnaar on Mon, 02/01/2016 - 09:26

Dear all,

I am running the CFDEMsolverIB tutorial and I want to visualize my CFD and DEM results in paraview. To visualize this I obtained VTK files via adding reconstructCase="true" to the parCFDEMrun script & command and as I am running on multiple processors I had to add the "reconstructParmesh" command to the parCFDEMrun function.

Now when running the simulation I fall into the following error:

--> FOAM FATAL ERROR:
cell, tetFace and tetPt search failure at position (-0.00079004318 -0.001127873 0.0044064325)
for requested cell 0

Particle does not reach steady state sedimentation velocity

Submitted by r2d2 on Sun, 01/31/2016 - 17:16

Hey there,
I have a minor problem with the sedimentation velocity of a particle. The Particle is located on the top of an tube and shall sediment to the ground of the tube. I am have chosen the following parameters in the couplingProperties file:

modelType "A";

forceModels
(
DiFeliceDrag
//SchillerNaumannDrag
//KochHillDrag
//MeiLift
//virtualMassForce
gradPForce
viscForce
Archimedes
);

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