Experimental insights into the segregation of aerated bimodal particle-gas mixtures under shear

Lipiejko, Natalia and Jones, Thomas J. (2026) Experimental insights into the segregation of aerated bimodal particle-gas mixtures under shear. Powder Technology, 480: 122614. ISSN 0032-5910

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Abstract

Gas–particle mixtures occur in numerous geophysical phenomena and industrial processes, yet describing and understanding their flow properties remains a challenge. The difficulty in modelling granular mixtures comes from having to consider the characteristics of individual particles, properties of the aerating gas, and the complex gas–particle interactions, all of which often change both temporally and spatially. Here, we present an experimental investigation into the properties of sheared monodisperse and bimodal granular mixtures at various levels of aeration. The effects of applied shear on particle segregation were analysed. At sufficiently high air velocities, monodisperse columns exhibit bubbling fluidisation, while bimodal columns segregate into a layer of coarser glass beads overlain by a layer of smaller particles. Our experimental data indicate that applied shear can suppress the formation of bubbles and promote a homogenous non-bubbling aeration in monodisperse columns, while for the bimodal columns, shear was observed to delay and suppress segregation and the column remained in a mixed state.