TY - JOUR

T1 - Suppression of viscosity enhancement around a Brownian particle in a near-critical binary fluid mixture

AU - Fujitani, Youhei

N1 - Publisher Copyright:
© 2020 The Author(s).

PY - 2020

Y1 - 2020

N2 - We consider the Brownian motion of a rigid spherical particle in a binary fluid mixture, which lies in the homogeneous phase near the demixing critical point, assuming that neither component is more attracted by the particle surface. In a recent study, it was experimentally shown that the self-diffusion coefficient first decreases and then reaches a plateau as the critical point is approached. The decrease should reflect the critical enhancement of the viscosity, while the plateau was interpreted as representing the suppression of the enhancement due to the shear around the particle. To examine this interpretation, we take into account the local shear rate to calculate the dependence of the drag coefficient on the particle speed, and then utilize a Langevin equation to calculate the self-diffusion coefficient.

AB - We consider the Brownian motion of a rigid spherical particle in a binary fluid mixture, which lies in the homogeneous phase near the demixing critical point, assuming that neither component is more attracted by the particle surface. In a recent study, it was experimentally shown that the self-diffusion coefficient first decreases and then reaches a plateau as the critical point is approached. The decrease should reflect the critical enhancement of the viscosity, while the plateau was interpreted as representing the suppression of the enhancement due to the shear around the particle. To examine this interpretation, we take into account the local shear rate to calculate the dependence of the drag coefficient on the particle speed, and then utilize a Langevin equation to calculate the self-diffusion coefficient.

KW - colloids

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U2 - 10.1017/jfm.2020.815

DO - 10.1017/jfm.2020.815

M3 - Article

AN - SCOPUS:85183479061

SN - 0022-1120

VL - 907

JO - Journal of Fluid Mechanics

JF - Journal of Fluid Mechanics

M1 - A21

ER -