“Shear Acoustic Wind” Acting on Particles Embedded in a Liquid Crystal

Abstract

We present here a theory of a specific force acting on the particles embedded in a liquid crystal (LC) if a “fast” (viscous) shear wave is excited in the LC layer. The origin of this force is very similar to the so-called “ponderomotive forces” acting on the electrons or bubbles in liquids in the presence of spatially non-homogeneous periodic fields (electric in the first case and acoustic in the second). We show that one can use this effect for manipulation, orientation through sedimentation, and separation of particles, including carbon nanotubes. This article is mostly focused on the case of elongated particles in a nematic liquid crystal medium. However, more general consideration is also presented.