Directed drift of a deformable axisymmetric particle on a vibrating substrate

Dr Marina Terzi,
Le Mans University

Abstract:
It is known that solid particles posed on a vibrating substrate can move on it. Under certain conditions, the particle can drift in a particular direction. Such drift can be potentially used to activate components of micro-devices, to transport powder and to clean dry surfaces from dust. The drift can be initiated e.g. by exciting Rayleigh acoustic wave in the substrate which causes friction at the contact between particle and substrate, which, in turn, creates an asymmetry between the direction of the wave and against it. This talk is about the required wave characteristics to obtain the directed drift as well as about its possible directions. While a material point is capable of sliding only in the direction of the wave, our model of deformable particle predicts particle drift in the both directions. Contact of an axisymmetric deformable particle with an elastic half-space is described via the known Hertz-Mindlin solution upgraded into a so-called method of memory diagrams (MMD) valid for an arbitrary acoustic excitation. The drift direction is determined by the direction of the friction force in a low normal compression phase that fosters slip, in accordance to the Coulomb friction law. In closing, I will talk about the experimental validation attempts and the related challenges.