Transverse transport and trapping of submerged structures due to water wave refraction
Phys. Rev. Fluids 11, 064801 – Published 1 June, 2026
DOI: https://doi.org/10.1103/6884-kzv4
Abstract
Waves refract when traveling over water of variable depth, and the theory of radiation stress implies consequent forces imparted to the bottom topography. Such forces may be relevant for deformable boundaries and submerged objects that are free to move, but such wave-structure interactions have yet to be experimentally observed nor utilized in applications. Here we demonstrate such effects at the laboratory scale by introducing experimental techniques for studying the movements of submerged structures due to water waves. Asymmetrically shaped bodies are shown to move perpendicularly to plane traveling waves, and visualizations of the distorted wave fields are consistent with a mechanism based on refraction in the shallow layer over the structure. Further, we show how this effect can be exploited to stably position or "tweeze" objects within focused wave fields. Simplified calculations suggest that refractive redirection of momentum flux can explain these outcomes, and the form of the wave field and geometry of the body can be used to control forces. The systems presented here are hydrodynamic analogs to acoustic and optical transport and trapping, suggesting generalizations that could guide further strategies for wave-based motion control.
