CFDEM®coupling - User Forum

I noticed that the coupling interval from the hopper tutorial has different numbers in the input file of LIGGGHTS (100) and in the couplingProperties from OpenFOAM (250). I guess that the numbers should be the same.

Further more I have seen that the parallelization is in different directions. I don't know if that is on purpose.
Can anyone tell me what the best way is to split for parallelization? In DEM best should be that all processors have same # of particles. Does it make sense to split the fluid domain in the same direction?

Thanks

Hi,

I wonder how to speed up CFDEM.

I am running a particle-laden jets. To reach the steady state, I have to run for a long time.

Could anyone tell me where I can modify to speed up, especially in DEM/in.xxxx

Thanks.

rq

Hello,

It seems (from your email) that angular momentum for the solid spheres are not taken into account. I think this is a problem, in absence of angular momentum will change the dynamics of the particle.

Consider a ball moving upwards in a a cross flow (i.e. ball moving upwards in +ve y direction, flow in +ve x direction), then deflection of ball from the straight path would be different if angular momentum is considered.

Any comments,
Abhishek

Hello,

I have to solve a problem of a liquid filling into an enclosed space have loose objects (balls). To model this, it needs coupling of CFD (with VOF) and DEM. VOF is supported by openfoam, and I wonder if CFDEm simulations are possible using the VOF solver of openfoam?

Regards,
Abhishek Basak

Hi Christoph,
please put cfdem for direct download as git is not working with the proxy.
thanks in advance,
Samantaray

Hi,

Could anybody tell me how to setup the various time step in cfd-dem, i.e.

CFD/constant/couplingProperties
DEMts
couplingInterval

CFD/system/controlDict
deltaT

DEM/in.xxxx
timeStep
fix cfd all couple/cfd/force couple_every 100 mpi

How to keep these time variables consistent?

And anything else has to be adjusted if deltaT in controlDict changed?

Thanks.

rq

Hi cfdemers,

I found the magnitude of Achimedes Buoyancy force is low by the 4th order.

Please check the magnitude of this force.

BTW, I suggest use Achimedes buoyancy force instead of lift force. The latter is often referred to the normal force to ambient flow induced in shear flow.

Thanks.

rqwang

Hi

I am having trouble with stability in my model and I was wondering if anyone can give me some idea as to what is causing the problem.

I have simple laminar flow between two concentric cylinders, initially starting from rest. A moving wall boundary on the inner wall starts moving the fluid, and eventually the whole domain gets "up to speed". The particles in the flow are initially evenly distributed, but as the flow speeds up, the particles start moving towards the outer wall.

Hi users,
I am new to CFDEM. I am good in LIGGGHTS but I dont know how to do with CFDEM. Please can you provide a simple example to illustrate CFDEM? For example, I have run simulation using LIGGGHTS. Now how to write script or what to do so that I can couple and do simulation in CFD? Is there any example file like example file of LIGGGTHS.
Thanks,
Amrita K

Does any one here know how the coupling between the CFD code and the DEM code is done?
I mean, first one have to compute fluid velocity and pressure accounting from volume fraction through mass conservation and momentum equations.
This operation is generally processed by a velocity-pressure coupling algorithm like SIMPLE, PISO, Chorin projection, etc....
Does someone have some insights on this process and specifically how the mass conservation equation accounting the volume fraction is used for this purpose?