Reply To: ANSYS fluent – Rocky DEM coupling

[Saeed]

Dear Rob and Vinicius,

Thank you for your suggustions. 

1- about the semi-resolved so basically i can not use semi-resolved if i want to measure the drag force and it can just be used for particles distribution . Correct ?

I have done simulation with 24R1 too with a fine mesh and 0.001s time step and same issue comes up that simulation does not proceed. 

2- Before Rob mentioned that he suggusts that instead of using a tetra/hexa combination just use tetra with lower time step. I ran a simulation with 0.001 and 0.0005 time steps and 4.67e-6 DEM time step  with the attached mesh. the one with 0.001s crashed and gave the follwing error and simulation stopped before even 0.1s of simulation output : 

DEM-CFD critical explicit time step:
6.19% of the particles exceeded 50% the CFD critical explicit time step.
3.23% of the particles exceeded 75% the CFD critical explicit time step.

The one with 0.0005s time step , went to 9s and gave the following error and particles agglomorated (picture attached )but the simulation were still running: 

DEM-CFD critical explicit time step:
0.183% of the particles exceeded 50% the CFD critical explicit time step.
0.0913% of the particles exceeded 75% the CFD critical explicit time step.
0.0913% of the particles exceeded 100% the CFD critical explicit time step. collected in 11 events of CFD forces. 

I want to know why it took the simulation 9s to give the error and suddenly got unstable , if there is a problem why it did not gave the error begining of the simulation ?

 

3- i ran one or two with SPH and particles agglomorated , i will try again SPH and with lower time step of DEM and let you know.

Thanks