Shear-thinning viscosity is a non-Newtonian behaviour that active particles often encounter in biological fluids such as blood and mucus. The fundamental question of how this ubiquitous non-Newtonian rheology affects the propulsion of active particles has attracted substantial interest. In particular, spherical Janus particles driven by self-diffusiophresis, a major physico-chemical propulsion mechanism of synthetic active particles, were shown to always swim slower in a shear-thinning fluid than in a Newtonian fluid. In this work, we move beyond the spherical limit to examine the effect of particle eccentricity on self-diffusiophoretic propulsion in a shear-thinning fluid. We use a combination of asymptotic analysis and numerical simulations to show that shear-thinning rheology can enhance self-diffusiophoretic propulsion of a spheroidal particle, in stark contrast to previous findings for the spherical case. A systematic characterization of the dependence of the propulsion speed on the particle's active surface coverage has also uncovered an intriguing feature associated with the propulsion speeds of a pair of complementarily coated particles not previously reported. Symmetry arguments are presented to elucidate how this new feature emerges as a combined effect of anisotropy of the spheroidal geometry and nonlinearity in fluid rheology.
Toward a theoretical framework for self-diffusiophoretic propulsion near a wedge
School of Mathematics and Statistics, The Open University（开放大学数学与统计学院）；Max Planck Institute for Dynamics and Self-Organization (MPI-DS)（马克斯·普朗克动力学与自组织研究所）；Rudolf Peierls Centre for Theoretical Physics, University of Oxford（牛津大学鲁道夫·派尔斯理论物理中心）
Collinear Swimming of a Squirmer Pair in Newtonian and Shear-Thinning Fluids
Santa Clara University（圣克拉拉大学）；University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Towson University（陶森大学）；New Jersey Institute of Technology（新泽理工学院）；Texas A&M University–Corpus Christi（德克萨斯农工大学科珀斯克里斯蒂分校）
