Topographically controlled, breaking-wave-induced macrovortices. Part 1. Widely separated breakwaters
M. BROCCHINI a1, A. KENNEDY a2, L. SOLDINI a3andA. MANCINELLI a3 a1 D.I.Am., Università di Genova, 16145 Genova, Italy a2 Department of Civil & Coastal Engineering, University of Florida, Gainesville, FL 32611-6590, USA a3 Istituto di Idraulica, Università Politecnica delle Marche, 60131 Ancona, Italy
In this and the companion paper (Part 2) we examine experimentally, computationally, and analytically the behaviour of breaking-wave-induced macrovortices during startup conditions. Widely separated breakwaters and rip current topographies are chosen as opposite ends of the parameter space. Part 1 examines generation mechanisms using phase-resolving and phase-averaged approximations, and suggests several simple predictive relations for general behaviour. Vortex trajectories and shedding periods for wave breaking on widely spaced breakwaters are also considered in detail. Results show broad agreement with theoretical trajectories. Predictions of vortex shedding periods on breakwater heads show excellent agreement with computations. Part 2 examines startup macrovortices on rip current topographies using computations and laboratory experiments, and changes in behaviour as the system transitions from wide to narrow gap width.