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Time-dependent wave forcing in computational nearshore hydrodynamics

2003; Springer Nature; Linguagem: Inglês

10.1016/b978-008044046-0/50234-7

1860-4838

A KENNEDY, F SHI, J KIRBY,

Coastal and Marine Dynamics

This chapter examines the computational near-shore wave transformation and wave-induced currents, concentrating on phase-averaged wave drivers and time-domain circulation models. The chapter focuses on the effects of unsteady wave forcing. The neglection of unsteady forcing is shown to lead to an incorrect representation of slow time scale Reynolds stresses, with resulting errors in circulation. Finally, closure problems are introduced in the chapter that will become important in future work. Water waves in the near-shore transform considerably from deep-water: refracting and diffracting under the influence of bottom topography and nearshore currents; change height and shape as they approach the shoreline; and finally break and dissipate most of their energy near the shoreline. In particular, the chapter discusses the differences between time-dependent and time-independent wave forcing. For the rip current example illustrated in the chapter, response times are on the order of wave group time scales, but the other classes of flows—such as longshore currents—have significantly longer response time scales.