Columbia University, Departments of Chemical Engineering
Multiphase granular flows are ubiquitous in nature and encountered in process units throughout the chemicals, energy, and pharmaceuticals industries. Granular flows exhibit a rich set of behaviors traversing regimes of solids, liquids, and gases. Despite the importance, the physics of these flows is still poorly understood, leading to difficulties in predicting geological flows and significant problems in scale-up and optimization of process units as compared processes involving only gases and liquids. Key challenges to understanding and optimizing granular systems include: (1) experimental characterization of flow within 3D opaque systems and (2) creating controllable, predictable, and optimized behavior in heterogeneous, mathematically chaotic flows. Here, we present the development and implementation of magnetic resonance imaging (MRI) techniques to rapidly image the 3D dynamics of gas, liquid, and granular particles in these multiphase systems. We identify key mechanisms in these flows and also anomalous flow phenomena. Further, we demonstrate how the combination of gas flow and vibration can create liquid-like flow instabilities in granular particles, introducing the ability to create controllable, structured flows. We also develop and use computational models to identify the physical mechanisms underlying anomalous and structured flows.