Treatment of free surface flow or even 3-phase flow

MFiX How to
#1

Hi, i am new to MFIX and really appreciate the open source community!
I want to model something similar to wet ball milling (for recycling application - but without wear or breakage consideration though). So, my model will contain a rotating drum in which I will have glass balls (DEM) and parts to be impacted (also DEM, second solid in the model), which are enclosed in a liquid (basically water), filling ca. 30% of the drum. So, this would either be a three phase problem (solid/solid-liquid-gas), or a liquid-solid/solid problem with a free surface flow (interface between water and air in the drum; note that the DEM solid can also be present in the air region) if the air is/cannot be modelled as the third phase, right? Does anyone have an idea how to model this properly in MFIX (preferably in the GUI)?

(Remark: my backround refers to commercial mechanical FEM codes, so CFD/DEM is relatively new for me)

Thanks in advance and best regards,
Marlon

MFIX- Hybrid model
#2

MFIX does not have the VOF type capability (e.g., interface reconstruction) that would be needed to resolve a free-surface flow.

#3

Thanks for the fast reply. But I was wondering whether the TFM-DEM Hybrid model could solve my problem, since in TFM there are 2 Eulerian continuous phases interacting anyway (in my case it would be water and air), while discrete solids (2 different DEM materials in my case) are dispersed in it. This way, it would be interpreted as gas-liquid-solid flow model without an actual “free surface flow”. Or am I wrong (as I said, I am not a fluid expert, rather in solid mechanics)?
Kind regards, Marlon

#4

The hybrid model assumes the TFM phases are a solid and imposes a solids-solids drag. You would need to get into the source code and make modifications to get the outcome you want.

#5

Mm okay, thanks for the clear response…