Experimental study of particle trajectories below deep-water surface gravity wave groups

Autor:	Paul H. Taylor, T. S. van den Bremer, Alison Raby, Colin Whittaker, R. Calvert
Rok vydání:	2019
Předmět:	Physics Stokes drift Mechanical Engineering Eulerian path Mechanics Particle displacement Condensed Matter Physics Conservative vector field Displacement (vector) Physics::Fluid Dynamics symbols.namesake Mechanics of Materials Particle tracking velocimetry Free surface symbols Particle
Zdroj:	Journal of Fluid Mechanics. 879:168-186
ISSN:	1469-7645 0022-1120
DOI:	10.1017/jfm.2019.584
Popis:	Owing to the interplay between the forward Stokes drift and the backward wave-induced Eulerian return flow, Lagrangian particles underneath surface gravity wave groups can follow different trajectories depending on their initial depth below the surface. The motion of particles near the free surface is dominated by the waves and their Stokes drift, whereas particles at large depths follow horseshoe-shaped trajectories dominated by the Eulerian return flow. For unidirectional wave groups, a small net displacement in the direction of travel of the group results near the surface, and is accompanied by a net particle displacement in the opposite direction at depth. For deep-water waves, we study these trajectories experimentally by means of particle tracking velocimetry in a two-dimensional flume. In doing so, we provide visual illustration of Lagrangian trajectories under groups, including the contributions of both the Stokes drift and the Eulerian return flow to both the horizontal and the vertical Lagrangian displacements. We compare our experimental results to leading-order solutions of the irrotational water wave equations, finding good agreement.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e4cd1d7f879554de13058f0c8b8cada4 https://doi.org/10.1017/jfm.2019.584 Zobrazit plný text záznamu