Michel Louge

Microgravity segregation in collisional granular shearing flows

Abstract: The presentation will discuss collisional granular shearing flows from the experimental, computational and theoretical standpoints. We will focus on the phenomenon of granular segregation where the separation of grains by size or mass is driven by spatial gradients in the fluctuation energy of the grains.

We will report experiments carried out in microgravity with a shear cell shaped as a race track and containing a mixture of two types of spherical grains. In those experiments, a gradient of fluctuation energy was produced between an inner moving boundary driving collisions among the grains and an outer, more dissipative boundary at the periphery of the cell. The grain segregation and the velocity statistics were captured by a rapid video camera and analyzed using computer vision software.

The talk will also outline a kinetic theory and numerical simulations incorporating individual impact parameters measured in the laboratory. We will compare the corresponding profiles of granular concentration, mean velocity and fluctuation energy with the experimental results.

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