Boundary-induced autophoresis of isotropic colloids: anomalous repulsion in the lubrication limit. (22nd December 2016)

• Record Type: Journal Article
• Authors: Yariv, Ehud
• Is Part Of: Journal of fluid mechanics. Volume 812(2017)
• Page Start: 26
• Page End: 40
• Publication Date: 2016-12-22
• Subjects: colloids, -- low-Reynolds-number flows, -- lubrication theory; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2016.816
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract : When suspended in a liquid solution, chemically active colloids may self-propel due to an asymmetry in either particle shape or the interfacial distribution of solute absorption. We here consider a chemically homogeneous spherical particle which undergoes self-diffusiophoresis due to the presence of nearby inert wall. In particular, we focus upon the near-contact limit where it was recently observed (Yariv, Phys. Rev. Fluids, vol. 1 (3), 2016, 032101) that the solute-concentration profile within the narrow gap separating the particle and the wall cannot be uniquely determined by a gap-scale analysis. We here revisit this near-contact limit using matched asymptotic expansions, the inner region being the gap domain and the outer region being on the particle scale. Asymptotic matching with the Hankel-transform representation of the outer distribution of solute concentration serves to determine both the scaling and magnitude of the corresponding inner profile. The ensuing gap-scale pressure field, set by a lubrication mechanism, gives rise to an anomalous particle–wall interaction, scaling as an irrational power of the gap clearance.