On the role of meniscus geometry in capillary wave generation

Abstract

Capillary waves, surface waves whose restoring force is dominated by surface tension, have been an important part of experimental fluid mechanics for many years. Capillary waves are typically generated by a vibrating wave generator which may be the walls of the tank containing the liquid or a separate object. In both cases, a meniscus exists at the interface between the liquid and the wave generator. Though this meniscus is due to the same surface tension that controls capillary waves, its effect on capillary wave formation has not been studied. Herein we present experimental results showing that such a meniscus is needed to form capillary waves, that the lack of a meniscus (a flat interface at the wall) prevents the formation of these waves, and that a meniscus of either positive or negative curvature serves equally well in enabling capillary wave formation.