Local solid volume fraction MFIX DEM

[gaoxi]

Convergence of the polydispersity drag models in MFIX-PIC

I am surprised that the DEM solver is available to use with the polydisperse drag models in MFIX. In the current implementation, they were derived for and should only be applied to TFM (i.e. Eulerian solids). Also, it is my impression that polydisperse drag models, in general, make the most sense when a system has thousands of particles per cell, and I doubt that is the case for any DEM simulation, and given your input sheet, not the one you are running. As for PIC, if you want Gidaspow-Blend…

@maclarke

As for PIC, if you want Gidaspow-Blend drag, please do not apply the _PCF version (or any of the other _PCF drag models available in MFIX). The program will definitely fault because solids fraction by phase is not tracked through a full simulation, as it is unnecessary for the solids model.

For MFIX-PIC, the drag models are employed through total solids fraction only, and by default the diameter of phase 1, hence why the _PCF models don’t make sense. You certainly CAN track solids fraction by phase, if you want to, but I would suggest doing so through a UDF where you might apply a more Lagrange-friendly polydisperse drag function.