Modeling chemical and hydrodynamic interactions in phoretic suspensions
Orateur : Akhil Varma / Doctorant Ladhyx, Paris
Abstract : Phoresis is a physico-chemical mechanism by which certain microscopic colloids drift through gradients of a solute concentration field in a fluid. This mechanism is exploited by autophoretic particles - a class of synthetic colloids which are chemically active, to achieve self-propulsion. In their suspensions, these self-propelling particles influence each others’ motion through chemical and hydrodynamic interactions. Modeling these interactions is a subject of intense research over the past decades to explain the observations of their large-scale collective behaviour as well as to aid in the design of controlled transport at microscopic scales. Most efforts so far rely on the superposition of far-field approximations for each particle’s signature, which are only valid asymptotically in the dilute suspension limit. A systematic and unified analytical framework based on the classical Method of Reflections (MoR) is developed here for both Laplace and Stokes’ problems to obtain the multi-body interactions and the resulting velocities of phoretic particles, up to any desired asymptotic order of accuracy. Some examples are then shown where the MoR framework, limited to three-body interactions, can provide insight into the collective dynamics in phoretic suspensions.
Date et lieu : jeudi 12 septembre 2019 à 11h dans la salle de séminaire IRPHE