A Three-dimensional Numerical Study of the Green Island Wake

Abstract

Vortex shedding downstream of Green Island due to passing of the Kuroshio was numerically studied using the three-dimensional Princeton Ocean Model Temporal and spatial characteristics of the vortex street were analyzed at different Reynolds numbers tidal levels wind directions and typhoon wave The model results were compared with in-situ measurements of the shipboard survey and MODIS (Moderate Resolution Imaging Spectroradiometer) satellite image datasets for vortex shedding Numerical results suggest that the vortex spatial ratio (aspect ratio and dimensionless width) temporal scales (Strouhal number) and propagation speed of the vortices can stretch twist and interact in different water depths However we found that the higher Reynolds numbers corresponded to lower vortex shedding periods (VSP) Higher water depth corresponded to higher VSPs The value of 0 23 with the realistic model These results roughly agree with an observation obtained by (Chang et al 2013) On the other hand Wind stress also affects the velocity of oceanic current The current velocity is higher under the southwest wind than under the northeast one The southwest wind tends to increase current velocity and thereby strengthens vortex shedding The Lanyu wake and the Green Island wake are induced by the main Kuroshio pathway and its swings By wake tracking it was possible to describe the interaction between eddies and ocean currents Then it also indirectly affects the vertical characteristics of the green island wake

Date of Award	2019
Original language	English
Supervisor	Shih-Chun Hsiao (Supervisor)