CFDEM®coupling - User Forum

Hi all,

I hope to make the fluid boundaries change with the DEM boundaries. In this case, the CFD boundary will cover the DEM boundary at any time. Is there any method to achieve this? Thanks !

Best regards
XIA

Hi,

Can you please suggest me where I can find the governing equation for the CFD-DEM coupling that LIGGGHTS uses. I need to use them for some publication.

Hi,
I found that the rho in settlingTest case is 10, and when I simply change it to 1000 which is supposed to be the density of water, the motion of particle becomes very unnature. The velocity becomes unrelastic large.

I found that this might be related to the drag force model, cause when I comment the force model de felice, and only keep the Archimedes force, the result seems to reflect correctly to the change of fluid density.

Could someone help with this question. Am I misunderstanding something about rho?

Dear CFDEM Community

I am using Unresolved CFDEM to simulate particle infiltration in bed. I am facing problem now to simulate the case for larger duration due to high memory requirements as number of particles increase as simulation progresses and eventually gets killed even on large Linux-clusters. I know that Unresolved CFDEM has limit in terms of number of particles (oder of ~10^7) but my simulation gets killed despite total number of particles are less than the limit specified above.

Hello everyone.
By investigating the Ergun test case among the tutorials I noticed that if I run the case in noSlip conditions the pressure drops decrease, why is that? The no-slip condition should add an additional source of dissipation for the flow. How can the pressure drops decrease if I'm adding friction sources to the fluid flow?
Can you help me understand this effect, please?

In the periodic channel flow of cfdemSolverPiso there is neither any Pressure gradient nor any inclined plane gravity force - so I could not understand what is the driving factor of this flow.

P.S. I am an extreme newbie (2nd Year Chemical Engineering Undergraduate Student). Please help me to understand the concepts :)

Hello all

I am facing this strange problem using 'fix freeze' command. I generated bed consisting of large particles (type 1). I want my bed to not move at all when injecting small particle (type 2) along with the fluid from inlet. To achieve this, I tried freezing the large bed particle (type 1). In my run script, I group the type 1 particles and then freeze them, the freeze command is located after cfd fixes, so that the forces coming from CFD side also becomes zero and bed should remain stable.

Hi,
I'm running a case with an filtration application. It is laminar flow, a set of fixed particles as a membrane and some moving particles within the flow.
After a certain amount of time, the kinetic energy increases very fast and the run breaks up.

What could be the reason for the increase in kinetic energy?

Hi,
I am about to make a simulation where the first part of the domain is nonsloping, but the second part of the of the domain should be sloping. It is a beach where the first part is at constant depth and then the sloped part, where the depth is decreasing until reaching the surface. Is it possible to make such a domain in LIGGGHTS?
I have attached a picture of the domain I want to create.

Hello everyone.