Particulate patterns generated by liquid templates

Abstract

We characterize the assembly of microscopic particles in patterned beds. The particles are immersed in a liquid template generated by vibration. We study, at the same time, the waves in the liquid surface, and the topography of the bed. Results show that the surface waves are travelling, harmonic and capillary waves, in contrast with previous studies that examined Faraday subharmonic waves. The patterned bed presents an alternation of annular ridges and troughs, with a characteristic lengthscale similar to the surface wavelength. The amplitude of the variation of the bed thickness increases as the mean bed thickness increases, and as the vibration frequency decreases; this is explained in terms of a Shields number that depends on both variables. In turn, the localization efficiency of the particles decreases with the bed thickness but increases with the pattern characteristic lengthscale. We discuss assembly design and compare with dry granular systems.