unresolved CFD-DEM for DEM particle size larger than CFD cell size??

Submitted by almonds22 on Wed, 08/03/2016 - 07:48

Hi all,

Regarding the CFDEM program, I've studied the governing equations behind the unresolved vs. resolved CFD-DEM.

As we're all aware, the unresolved CFD-DEM method is applicable only if the DEM particle size is significantly smaller than the CFD cell size.

However, I was wondering...could we use the unresolved CFD-DEM if the DEM particle size is significantly larger than the CFD cell size?? Will that cause any convergence issues ? Will that affect the accuracy of the results? Can we get the same realistic results ?

I would be very grateful if anyone could share their experience...as that's something I've been thinking for a long time...

Kevin

Forums:

medvedeg | Wed, 08/03/2016 - 14:37

If the particle size is significantly larger than the CFD cell size, this means that there is somewhere at least one cell with zero void fraction. The momentum equation here becomes something not looking like a differential equation... This is one of the possible explanations.

Alexander Podlozhnyuk

almonds22 | Sat, 08/06/2016 - 06:25

Hi Alexander,

Thank you very much for your reply and the clarification!

Well I guess we could also include a void fraction or smoothing model for the unresolved approach in the event the DEM particle size exceeds the CFD mesh cell size.

Kevin