Intruder Interaction in Bubble-Free Vibrated Gas-Fluidized Beds*

Recently, a regime of bubble-free gas fluidization was demonstrated using gas flow rates and vibration conditions too weak to fluidize particles on their own. Here, we demonstrate the dynamics of intruders sinking through this bubble-free fluidization state. When two intruders are arranged vertically, they undergo drafting-kissing-tumbling instabilities with similar characteristics to those observed in Newtonian fluids. When intruders are side-by-side, intruders interact in a way that they exchange the lead in descent. Effects of varying gas flow and vibration conditions as well as intruder size and density are reported.

This work was funded by: Office of Naval Research grant N00014-23-1-2041 and National Science Foundation grant 2144763