Reply To: ANSYS fluent – Rocky DEM coupling

[Vinicius]

Hello Saeed, 

I see you are using 23R2 so semi-resolved is not a good option in this case, since it does not support turbulent flows. The reason why you don't see a drag law selection option is because there isn't one. The semi-resolved approach does not rely on any correlations for computing the drag force. On top of that, you would need a super fine mesh. 

The error you are getting, the "DEM explicit time step" one, is raised when the DEM time step is too large to handle the drag force. Since the drag force is computed explicitly, if the time step is too large, the solution diverges. Try to lower Rocky's timestep and check how it goes. Also, keep the ratio between Fluent and Rocky time steps below 1e3. Finally, as pointed out by Rob, smooth out the transition between the cell zones. My final suggestion is to keep the impeller still as a first test, without the sliding mesh, just the bare minimum. Try to isolate the issue.

Since particles are big, have you checked Rocky's SPH approach?