Mixing resolved beyond the Batchelor scale

fig_6Here we present high resolution experiments allowing for the precise quantication of the evolution of concentration distributions of a single lamella experiencing diffusion, stretching and aggregation with other lamellae.

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Revealing the frictional transition in shear thickening suspensions

The sudden and severe increase in the viscosity of certain suspensions above an onset stress is one of the most spectacular phenomena observed in complex fluids.  This shear thickening, which has major implications for industry, is a long-standing puzzle in soft-matter physics.  Recently, a frictional transition was conjectured to cause this phenomenon. Using experimental concepts from granular physics, we provide direct evidences that such suspensions are frictionless under low confining pressure, which is key to understanding their shear thickening behavior. More from PNAS here (2017_PNAS_Clavaud)

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Taylor’s experiment in a periodically sheared particulate suspension

We revisit Taylor’s experiment investigating the evolution of a blob of dye in a periodically sheared suspension of non-Brownian particles. Above a critical strain amplitude, particulate suspensions are subject to phase transition where reversibility is lost and particles fail to return to their original positions. We investigate the effect of this transition on the dispersion of a blob of dye. Beyond the critical strain, the dispersion of the blob is found to increase significantly. The dispersion coefficient of the blob of dye is measured and compared to the self-diffusivity coefficient of the particles. More from Phys. Rev. Fluids here  [2016_souzy_prf].TaylorExp_Souzy.png