(364d) Real-Time Magnetic Resonance Imaging of Dynamic 3D Granular Systems

Experimental measurements of granular dynamics are vital to test theoretical models and validate numerical simulations. Magnetic resonance imaging (MRI) can provide non-intrusive measurements of particle position and particle velocity of opaque 3D granular systems. However, one major limitation has been the low temporal resolution of particle velocity measurements limiting the application of MRI to stationary systems.

In the present work we combine imaging hardware developments, granular materials’ engineering and accelerated MRI sequence protocols to increase drastically the temporal resolution of MRI based measurements of granular materials. We apply the new methodology to a variety of dynamic granular systems such as bubbling fluidized beds, granular flow around gas bubbles and the impact of intruders into granular systems. These measurements provide fresh insight into hitherto undiscovered facets of granular dynamics, such as the non-negligible vorticity of granular flow around gas bubbles in fluidized beds. The methodology developed could be used in the future to study other dynamic granular phenomena, such as the jamming transition, granular segregation or wave propagation.