cfdemSolverPISO constant inserting particle while CFD calculation

Submitted by Donald Trump on Thu, 07/26/2018 - 19:03

Dear all, I wanted to simulate the constantly inserting particles interaction with the gas flow.
However, at cfdemSolverPISO, when you use fix ID group-ID couple/cfd couple_every N mpi, it only says the CFD COUPLING was established, but the solver will not go to do the CFD calculation, like solve the velocity and other fluid field.
Once the DEM steps were done, and CFD process began to calculate the fluid field, I will not insert any particles then.
How can I make this happen if I still need to insert particles when the openfoam was called to solve the fluid field?

Thanks!

paul | Fri, 07/27/2018 - 09:15

"CFD COUPLING was established" is a vestigial statement and couple_every N does not play a role anymore since coupling is mostly done on the CFDEMcoupling-side of things.

>the solver will not go to do the CFD calculation, like solve the velocity and other fluid field.
> Once the DEM steps were done, and CFD process began to calculate the fluid field
This sounds exactly correct. What is your problem?

I'd suggest using fix insert/pack or insert/stream for continuous / periodic particle insertion

Donald Trump | Fri, 07/27/2018 - 15:01

Hi Paul,

Thank you very much for your reply! My problem is I want the CFD calculation (using openfoam solving the fluid field) happening simultaneously (or at least seems like that) when the program was running the DEM steps. Because I use the fix insert command in the DEM in.liggghts_run input file. Once the DEM steps finished, then the inserting process finished. However, I would like to see the fluid field calculation when the charging process was still going on. That is when running every some DEM steps in in.liggghts_run, I want to see the CFD calculation happening, not until all the DEM steps finished. The Current order set by the cfdemsolverPISO could not give me that information.

Donald Trump | Fri, 07/27/2018 - 15:11

I can only get the drag force when the program running the DEM steps in the in.liggghts_run. But I also want the fluid field information at that time. It looks like when using the Fix couple command in the DEM steps, I can only get the drag force acting on the particles, however, I want the state of the fluid at this, its velocity, pressure and so on, I am not sure the fix couple command will call the openfoam to do the calculation instantly at every N DEM steps. Or it's just simply calculate the particle fluid drag forces?

Yinxuan

Donald Trump | Sat, 07/28/2018 - 11:05

When set the CFD start time as 0 in the CFD system file, does this zero means the same time as DEM step start? Why in the output screen the CFD start time timesteps looks like following after all the DEM steps?