CFDEM®coupling - User Forum

Dear all,

I am doing a case study shown in tutorials of CFDEM and feel confused about "fix couple/cfd/force" and "fix couple/cfd/force/implicit" commands. The online documentation says the "fix couple/cfd/force" command contains contributions from all force models active in the CFD calculation, while the "fix couple/cfd/force/implicit" seems only contain the drag force coz it says "At every coupling time step the drag coefficient and the fluid velocity is transferred to LIGGGHTS".

I would like to install CFDEM (the latest version dated 27/11/2017) on Ubuntu 16.04 but when I use "cfdemCompLIG" command to compile LIGGGHTS, I get an error. I have installed OpenFOAM-3.0.1 (32 bit). I would appreciate any comments to resolve this issue. Please find below the error message I get:

An important aspect when using cfdemSolverPiso is that the particles must be smaller than the mesh cells in OpenFOAM.

In OpenFOAM one often does a pseudo-2D simulation where there is only one cell in Z-direction.

Hi everyone,

what would be the best way to carry out a one way couple simulation in which the particles "feel" the flow, but the flow is unafected by the particles?

Would setting alphamin to 1 achieve this correctly?

Hello,

Hi Everybody,

I am doing a CFDEM simulation of a microfluidic chip. On the OpenFOAM you have to use SI units. On the LIGGGHTS side you have choices. Since my microfluidic chip requires very small particles, I am working with micron units in the LIGGGHTs script.

Am I right believing the CFDEM-coupling assumes that we are working with SI units at all times? Checking the results in paraview it is obvious there is a big incongruence in the results from CFD and DEM. I imagine this arises from the code just tracking numbers and not the units, which he assumes to be SI.

Hi,
I've got a little issue with compilation on a new cluster (after everything has been running well with the old Uni cluster I was using, that is being decommissioned next month). I have compiled LIGGGHTS manually as a shared library, and it has created the liblmp_mpi.so in the LIGGGHTS /src directory, and i have the liggghts executable lmp_mpi. I compiled without VTK.

Hallo everybody.

I have a question about the rotation of cohesive particles when using CFDEM coupling. The particles start to rotate when they overlap with another particle or a wall. If I'm not using CFDEM coupling (only DEM), they don't rotate (see rotate.png). I don't use any rolling friction model. Can someone explain me this behaviour?

many thanks in advance.

Johannes

Dear all,

I am wondering whether we have a method about monitoring the permeability of the particles specimen. As far as I know, we can monitor the quantity of flow in the outlet boundary to calculate the permeability of the specimen manually. However, I haven't found a command about outputing the quantity of outflow. Could someone tell me which command should I use? or is there any possibility that we output the permeability of the specimen directly?

Thanks you very much!
Regards,
Rachel

Hi everyone,

Is the premium two-fluid CFDEM-Coupling meant ot be used only for fluid-gas-particles, or is it also possible to simulate two immiscible fluids in a fluid-fluid-particle simulation?

Cheers,
A