CFD-DEM with cyclic boundary conditions running extremely slow

Hi advanced users,

I found that in MFIX-CFD-DEM simulations, changing wall boundary conditions from no-slip to cyclic can slow down the simulations by a factor of 20 or more. Is it a bug? Is there any way to address this problem? I am using the MFiX-22.2.2. Actually, I also found the same problem using versions before MFiX-22.2.2.

For the cyclic BC, are you applying a mass flux or pressure drop? Please attach both input files.

test.zip (23.3 MB)
Hi Jeff,
Thanks for your reply. I used a mass flux. Attached are my case files. The number of particles is large. I used 24 processors in parallel.

I am not seeing that much of a difference. The cyclic case runs about twice as slowly as the no-slip-wall case. I used a 4x10x1 parallel decomposition with MFiX 22.4. I think the cyclic case runs slower due to the extra communication along the cyclic boundaries but it is not 20 times slower for me.

Hi Jeff,

Thanks for validating this. Maybe it is because the number of processors I am using for parallel running is not good for the cyclic boundary condition. I will try to use the same parallel settings as yours.