Streaming controlled by meniscus shape

TL;DR

This study investigates how controlling meniscus shape influences surface wave patterns and streaming flows, revealing symmetry-dependent flow structures and energy scaling in capillary-driven systems.

Contribution

It demonstrates that symmetric and antisymmetric meniscus shapes produce distinct wave modes and flow patterns, advancing understanding of capillary wave-induced streaming.

Findings

Streaming energy scales with the fourth power of forcing amplitude

Flow symmetry depends on meniscus shape

Streaming primarily originates from the Stokes boundary layer

Abstract

Surface waves called meniscus waves often appear in the systems that are close to the capillary length scale. Since the meniscus shape determines the form of the meniscus waves, the resulting streaming circulation has a structure distinct from that caused by other capillary-gravity waves recently reported in the literature. In the present study, we produce symmetric and antisymmetric meniscus shapes by controlling boundary wettability and excite meniscus waves by oscillating the meniscus vertically. The symmetric and antisymmetric configurations produce different surface capillary-gravity wave modes and streaming flow structures. The energy density of the streaming circulation increases at the rate of the fourth power of the forcing amplitude in both configurations. The flow symmetry of streaming circulation is retained under the symmetric meniscus, while it is lost under the antisymmetric meniscus. In our experiments, the streaming circulation primarily originates from the Stokes boundary layer beneath the meniscus and can be successfully explained using the existing streaming theory.