Stress and velocity fluctuations to probe the rheology of photoelastic granular avalanches

Granular fluidity has been central to the development of non-local constitutive equations, which are necessary for characterizing non-local effects observed in experimental granular flow data. However, validation of these equations has been largely computational, due to challenges in conducting precise laboratory experiments. In this presentation, we are introducing our photoelastic avalanche experiment, which does not only produce intriguing visuals, but also reveal the internal stress state of our 2D granular avalanches. We explore the role of velocity and stress fluctuations on the rheology of granular avalanches, and show that they could form a predictor of the stability of the internal state of a granular packing.