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arXiv · 2210.07977

Non-Brownian diffusion and chaotic rheology of autophoretic disks

R. Kailasham·Aditya S. Khair
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Abstract

The dynamics of a two dimensional autophoretic disk is quantified as a minimal model for the chaotic trajectories undertaken by active droplets. Via direct numerical simulations, we show that the mean-square displacement of the disk in a quiescent fluid is linear at long times. Surprisingly, however, this apparently diffusive behavior is non-Brownian, owing to strong cross-correlations in the displacement tensor. The effect of a shear flow field on the chaotic motion of a 2D autophoretic disk is examined. Here, the stresslet on the disk is chaotic for weak shear flows; a dilute suspension of such disks would exhibit a chaotic shear rheology. This chaotic rheology is quenched first into a periodic state and ultimately a steady state as the flow strength is increased.

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R. Kailasham, Aditya S. Khair. 2022-10-14. Non-Brownian diffusion and chaotic rheology of autophoretic disks. https://doi.org/10.1103/physreve.107.044609

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