https://hal-polytechnique.archives-ouvertes.fr/hal-01152258Yariv, EhudEhudYarivTechnion - Israel Institute of Technology [Haifa]Michelin, SébastienSébastienMichelinLadHyX - Laboratoire d'hydrodynamique - X - École polytechnique - CNRS - Centre National de la Recherche ScientifiquePhoretic self-propulsion at large Péclet numbersHAL CCSD2015[PHYS.MECA.MEFL] Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]Roura, Denis2015-05-15 20:28:542023-03-24 14:53:002015-05-15 20:28:54enJournal articles10.1017/jfm.2015.781We analyse the self-diffusiophoresis of a spherical particle animated by a nonuniform chemical reaction at its boundary. We consider two models of solute absorption, one with a specified distribution of interfacial solute flux, and one where this flux is governed by first-order kinetics with a specified distribution of rate constant. We employ a macroscale model where the short-range interaction of the solute with the particle boundary is represented by an effective slip condition. The solute transport is governed by an advection-diffusion equation. We focus upon the singular limit of large P\'eclet numbers, $Pe\gg 1$. In the fixed-flux model, the excess-solute concentration is confined to a narrow boundary layer. The scaling pertinent to that limit allows to decouple the problem governing the solute concentration from the flow field. The resulting nonlinear boundary-layer problem is handled using a transformation to stream-function coordinates and a subsequent application of Fourier transforms, and is thereby reduced to a nonlinear integral equation governing the interfacial concentration. Its solution provides the requisite approximation for the particle velocity, which scales as $Pe^{-1/3}$. In the fixed-rate model, large P\'eclet numbers may be realized in different limit processes. We consider the case of large swimmers or strong reaction, where the Damk\"ohler number $Da$ is large as well, scaling as $Pe$. In that double limit, where no boundary layer is formed, we obtain a closed-form approximation for the particle velocity, expressed as a nonlinear functional of the rate-constant distribution; this velocity scales as $Pe^{-2}$. Both the fixed-flux and fixed-rate asymptotic predictions agree with the numerical values provided by computational solutions of the nonlinear transport problem.