Faraday-waves contact-line shear gradient induces streaming flow and tracers' self-organization: from rotating rings to spiral galaxy-like patterns

Abstract

In this letter we experimentally demonstrate self-organization of small tracers under the action of longitudinal Faraday waves in a narrow container. We observe a steady current formation dividing the interface in small cells given by the symmetries of the Faraday wave. These streaming currents are rotating in each cell and their circulation increases with wave amplitude. This streaming flow drives the tracers to form patterns, whose shapes depend on the Faraday wave's amplitude: from low to high amplitudes we find dispersed tracers, a narrow rotating ring and a spiral galaxy-like pattern. We first describe the main pattern features, and characterize the wave and tracers' motion. We then show experimentally that the main source of the streaming flow comes from the time and spatial dependent shear at the wall contact line, created by the Faraday wave itself. We end by presenting a 2D model that considers the minimal ingredients present in the Faraday experiment, namely the stationary circulation, the stretching component due to the oscillatory wave and a steady converging field, which combined produce the observed self-organized patterns.

arXiv comment5 pages, 5 figures

References in corpus (9)

• Lagrangian tracers on a surface flow: the role of time correlations
• Aggregation of frictional particles due to capillary attraction
• Streaming patterns in Faraday waves
• Time persistency of floating particle clusters in free-surface turbulence
• Three-dimensional fluid motion in Faraday waves: creation of vorticity and generation of two-dimensional turbulence
• Heterogeneous structure of granular aggregates with capillary interactions
• From antinode clusters to node clusters: The concentration dependent transition of floaters on a standing Faraday wave
• Streaming controlled by meniscus shape
• Measurement of velocity field in parametrically excited solitary waves

Cited by in corpus (3)

• Spontaneous Formation of Star-Shaped Surface Patterns in a Driven Bose-Einstein Condensate
• Space-time resolved measurements of the effect of pinned contact line on the dispersion relation of water waves
• Capillary hysteresis induced by gap-resolved meniscus dynamics on Faraday instability in Hele-Shaw cells