CFDEM®coupling - User Forum

Hi every one,

I tried to run a settling simulation (similar to the settlingTestMPI) with the IB-Solver and found that the particle doesnt settle as it should be (Stokes as comparison). So I had a look at the calculation of the drag force and I think there is a mistake in the equations.

(1) volVectorField h = nufField*fvc::laplacian(U_)-fvc::grad(p_);
...
(2) drag += h[cellI]*h.mesh().V()[cellI];

I think both terms in equation (1) (nufField*fvc::laplacian(U_) and fvc::grad(p_)) should be multiplied with the density of the fluid.

Hi cfdemers,

Could anyone tell me how to setup a new particle injector?

I need such an injector that particles are randomly distributed on a disk.

The command of pour/dev makes my simulation discontinuous.

Thanks.

rq

Hi all,

When running the twoSpheresGlowinski-testcase the calculation stops right in the beginning with the message:

wait for file /couplingFiles/x1

Somehow the fix couple/cfd/force does not works properly in the latest LIGGGHTS-release (1.4.1). Is it just me or you have the same problems?

Regards,

Yansan

Dear developers & CFDEMers,
Some strange messages occur when I run the newest version of CFDEM, and none of cases run successfully.
My compiling process is same as the compiling tutorial --------setup_LIGGGHTS__OpenFoamR_CFDEM_2p0_on_Ubuntu1004_24052011.txt.
and everything goes well in the compiling process. (OF 2.0.1 debug version, LIGGGHTS1.4.1, CFDEM 2.1.0)

In the settingTestMPI directory, after the command ./Allrun.sh . the output message is following:

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