Article featured in Scientific American

November 05, 2021

Many industrial processes, including food, pharmaceutical, and mining, utilize bubbling fluidized beds. The dynamics of gas bubbles in these fluidized beds are mathematically chaotic and hard to predict, which create engineering challenges in scale-up, optimization, and operation. In our recent PNAS paper entitled “Dynamically structured bubbling in vibrated gas-fluidized granular materials”, we demonstrated that vibrating bubbling fluidized beds at a resonant frequency that is independent of particle properties and system size can transform the normally chaotic motion of gas bubbles into a dynamically structured configuration, creating reproducible, controlled motion of particles and gas. Existing continuum models for gas–solid flows struggle to capture fluid–solid transitions that are key to the formation of the structured bubbling pattern and thus cannot predict the bubble structuring. We proposed a constitutive relationship for solids stress that predicts fluid–solid transitions and hence captures the experimental structured bubbling patterns. The proposed model has been included in the open-source CFD software, MFiX, developed by the NETL. These advances in the creation of the structured bubbling pattern and the development of the continuum model could advance optimization of industrial processes that utilize bubbling fluidized beds. This paper was recently featured in a Scientific American article entitled “Tiny Vibrating Bubbles Could Make Mining More Sustainable”.