CFDEM®coupling - User Forum

Dear all,

I'm running the EngunMPI tutorial case on HPC using 40 cores and I detect that the number of cores for DEM and CFD parts the same, but in is not good becouse CFD parts is very sensetive for number of cores. In this situation I wanted to run DEM using 40 cores and CFD -5 cores. Is it possible to run CFDEM in this way?

Best regards, Furkhat

Hi, I am simulating a shearing test(Rheology test) of particle suspension. As it is well known that the viscosity of fluid is closely related to the solid fraction of the particles in a particle suspension system. So I was wondering if I want to consider this effect and use variable viscosity dependent on the solid fraction of the fluid cell, which part of the source code I should modify.

Thank you!

Dear All,
Hi,
I have a question about the value of timeStepFraction() that is returned by the line 136 in cfdemCloudIB.C and 218 in dataExchangeModel.C files. Can anybody explain me what value is showing this parameter? For your convenience, you can see its expression as follows:

scalar frac = ( (particleCloud_.mesh().time().timeIndex()-timeIndexOffset_)*particleCloud_.mesh().time().deltaT().value() - (couplingStep_-1) * couplingTime() ) / couplingTime();

When I use deltaT_CFD=2.5e-5s and deltaT_DEM=2.5e-7s, the case could run.
Part of the output info:

#cfd coupling
fix cfd all couple/cfd couple_every 100 mpi
nevery as specified in LIGGGHTS is overriden by calling external program (../cfd_datacoupling_mpi.cpp:77)
fix cfd2 all couple/cfd/force
restart ${restartstep} ../DEM/restart/liggghts_coupled.*
restart 800000 ../DEM/restart/liggghts_coupled.*

Hello,

since I am studying layer formation on membrane surfaces, I am looking for a simplified membrane model.
Up to now I found three of them:
1) one layer of spheres at a certain lattice
2) a rectangular (very thin) body inserted as granular
3) a simple wall

Hi,

Hello!

Hi everyone I have a problem compiling a cfdem case with my computer, I checked the files on another stronger computer and they're ok, but I think I'm missing something here. I'll appreciate any help of yours if you could tell me what is wrong.
mesh was built before - using old mesh
Decomposing case.
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |

Hi
One question:
I found the difference of defination in totalPressureDrop.m of Tend in ErgunTestMPI_cgs with ErgunTestMPI_restart
In ErgunTestMPI_cgs is :
Tstart = 0;
Tend = t_sim(length(t_sim));
deltaU=(Uend-Ustart)/((Tend-Tstart)/timeStepSize);
-------------
In ErgunTestMPI_restart is :
Tstart = 0;
Tend = t_sim(length(t_sim))
Tend=0.1
deltaU=(Uend-Ustart)/((Tend-Tstart)/timeStepSize);
----------------

How to define these? What is difference in ErgunTeshMPI and ErgunTestMPI?