CFDEM®coupling - User Forum

Hallo everyone,

I just started to use the cfdemSolverIB and I'm interested in the comparison between cfdemSolverPiso and cfdemSolverIB regarding the computational effort? When I apply the momentum exchange model ShirgaonkarIB, the computational time increases dramatically. Why is the momentum exchange as slow compared to e.g. KochHilldrag?

Thanks.

Johannes

Hi everyone,

When I run the attached case (5200 CFD cells and 90000 DEM particles) in 12 processors for a day (around 1 second in simulation), it always exceeds the memory limitation, which is 45 G and should be sufficiently large.

I tried to change the neighbor and neigh_modify settings but it didn't work. I cannot figure out why the case consumes such a large memory.

Please could anyone help to identify the reason or let me know if I made any mistakes.

Liggghts files are attached.

Thanks!

Jason

Hello,

I have just installed lights and am working through the tutorial document provided by Chris Stoltz. I was able to download and the tutorial and have double checked with the manual and can't find the error. The error revoles around the particle insertion. Below is the echo, and my code, my code is a copy of the code provided in the tutorials manual.

Any help on this would be much appreciated.

My code:
# Particle Insertion

Hi CFDEM folks and developers,

I have been playing around the fictitious domain method (FDM) to calculate the drag on a spherical particle for some time. It seems that there is a accuracy issue in terms of the drag calculation even with very fine mesh (error up to 30%).

A bench-marking test was performed to simulate the settling velocity of a single spherical particle falling freely in water. The simulation conditions are:

Hello, This is the firts time I write here, I am starting to work with CFDEM and I am trying to figure out the best way (the most accurate and optimized) to set up my simulation. I am trying to set up a dense system of particles and an inlet for fluid injection from a side.
I am using the run/tutorials/cfdemSolverIB/twoSpheresGlowinskiMPI/CFD/contant as reference for this case (I want to have the fluid behaviour as well as the particles/particles interactions). I am using cfdemSolverIB solver.

Hi Joself and Alice,

I believe I have gone through this forum carefully before asking this question. My modeling is in CGS unit. The major problem is now the CGS unit in the controldict file. I found in CFDEM/.../etc the file controldict_cgs_3.0.x but in fact this file does not contain the CGSCoeffs. Only SI and USCSC are seen here. Can you clarify whether this file will work if I copy it and replace the one in OpenFOAM/.../etc ? And can you provide the CGSCoeffs ? I dont think the controldict will work for CGS case without adding CGSCoeffts on it.

Thank you,

Hi Josef and Alice

I got a simple problem when CFDEM finishes running but the results stored in individual processor folders in CFD are not automatically copied and combined into time step folders. This rarely happens. Normally after running, CFD results from different processors will be copied into different time steps, so that I can use foamToVTK to convert to VTK files with respect to write _time_step. I did not change anything in the parCFDEM file, all paths and commands are the same.

Can you give me some hints, please ?

Thank you,

Regards,

Hi,
i have installed Openfoam 3.0.x and liggbhts and CFDEM. i have compiled them also. When i open the terminal i get the following error :
using CFDEM_ADD_LIBS_NAME=additionalLibs_ .
!!! ERROR !!!: CFDEM_ADD_LIBS_DIR/CFDEM_ADD_LIBS_NAME=/home/abhinandan/CFDEM/CFDEMcoupling-PUBLIC-/src/lagrangian/cfdemParticle/etc/additionalLibs_ does not exist.

Hi all! I have a question regarding on how to restart a CFDEM simulation.

I want to set up a case that check if the simulation was run before and continue the simulation from the last time step.
I can read a restart file with the last configuration, but how do I check if all the particles were inserted during the first run of the simulation and if I need to insert the rest to achieve the specified number of particles?

PD: I am using the ErgunTestMPI_restart case as a template
Cheers,
Mauro

Hi everyone,
I am trying to delete particles using "delete_atoms overlap" while coupling, but i found the delete_atoms command runs once, how can the command run frequently after particle position updated?
Thanks advance!

Best wishes
xiaobaishu