(77f) Rayleigh-Taylor Instability in Vibrated Gas-Fluidized Particles | AIChE

(77f) Rayleigh-Taylor Instability in Vibrated Gas-Fluidized Particles


Boyce, C. - Presenter, Columbia University
McLaren, C., ETH Zurich
Kovar, T. M., Columbia University
Penn, A., ETH Zurich
Müller, C. R., ETH Zurich
A Rayleigh-Taylor-like instability1,2 forms in a binary set of particles of different density subject to upward gas flow and vertical vibration3. “Fingers” and “bubbles” of light particles rise through heavy particles despite a lack of effective surface tension between the two types of particles. CFD-DEM simulations show that gas flow channels through fingers of lighter, larger particles due to a higher permeability of these particles to gas flow, locally increasing drag and causing these fingers to grow3. We demonstrate that the same physical mechanism causes an isolated “bubble” of light grains to rise and an isolated “droplet” of heavy grains to break up forming a binary branching pattern3. We explore how the combination of vibration and gas flow causes a bubble-free fluidization state in Geldart Group B and D particles and how this state can lead to other structured flow patterns.


(1) Rayleigh, J. W. S. B. Scientific Papers: 1881-1887; University Press, 1900.

(2) Taylor, G. I. The Instability of Liquid Surfaces When Accelerated in a Direction Perpendicular to Their Planes. I. Proc. R. Soc. Lond. A 1950, 201 (1065), 192–196.

(3) McLaren, C.; Kovar, T. M.; Penn, A.; Müller, C. R.; Boyce, C. M. Gravitational Instabilities in Binary Granular Materials. Proceedings of the National Academy of Sciences 2019, Accepted.