Ansys Employee
These types of unit don't work well with mixes like that as the weir won't split the phases. Weir based units are generally used with baffles and roughly even gas - liquid mixes with some oil and sand. To look at size separation I'd use multifluid VOF and DPM but be very careful with how I set up and interpreted the results.
From the video, the mixing and bubble/droplet creation is a function of the pump, so you know what sizes to start with. Read up on the Population Balance Model too, but I suggest you start with a very careful think about what you want to see, and how these devices work.