Hello everyone,
I am looking into a polydispersed fluidized bed, and currently modelling this with 4 phases with different particle sizes (range 50 to 178μm). The air rate is set to pull the finest of them the out the top. What surprises me somewhat is that the second most fine phase (at 70μm) is being pulled out also (in low quantities) when the 50μm is present. I have run the same simulation without this 50μm phase, and then none of the 70μm is carried out.
This is where I’m uncertain - is this an acknowledged effect? That coarser particles can be pulled out at what is supposed to be lower than terminal velocity when finer particles are present? It would be nice to know if this is a realistic effect that is actually captured in MFiX, or on the other hand perhaps an error that should be anticipated when phases are “close” with regards to particle size. At the moment I don’t have the experience to tell which is true.
Below: image on the right has a fourth phase of 10% 50μm inside. Air velocity is unchanged. Both images show Volume fraction of 70μm particles:
