Rheological Properties Of Fluidized Granular Matter

Abstract

Aerated granular media are important in several industrial processes; yet, their flow-behavior is poorly understood. On one hand, the well-known Geldart classification [1] divides granulates by their fluidization characteristics; on the other hand, the rheology of air-fluidized granular media has been recently investigated experimentally and theoretically [2], considering the fluidized bed as a homogeneous medium. We propose to link these two approaches by measuring flow curves for polydisperse particles of different diameter regimes ranging from 70 µm to 420µm. We find different rheological regimes depending on fluidization velocity and shear-rate, including Newtonian at low shear rate and Bagnoldian shear-thickening at high shear rate. We support the rheometry by light scattering to gain insights on the microscopic behavior of the aerated granular media in the future. [1] Geldart, D *Types of Gas Fluiditation*, 1973 [2] O. D*Angelo, A. Shetty, M. Sperl, and W. T. Kranz, *The manifold rheology of fluidized granular media,* 2023