A Coupled Hydrodynamic-Wave Model for Simulating Wave and Tidally-Driven 2D Circulation in Inlets

摘要

This study focuses on modeling the 2D, depth-averaged circulation of an ideal inlet that is driven by waves and tides using a coupled hydrodynamic-wave model. The circulation of an ideal inlet, consisting of a shallow bay of constant depth connected by a relatively narrow inlet to a sloping coastal shelf region, is studied. Circulation within the inlet is examined during the flood, slack, and ebb phases of the tidal cycle. The ideal inlet is also simulated with only wave forcing to better understand the effect of wave-current interaction on the circulation. The influence of the various forcings on bay/inlet circulation is further investigated by the introduction of Lagrangian tracers. Wave-current interaction is simulated by iteratively coupling the depth-integrated ADCIRC-2DDI hydrodynamic model to the 2D phase-averaged spectral wave model SWAN. ADCIRC-2DDI is a fully developed, 2-dimensional, finite element, barotropic hydrodynamic model capable of including wind, wave, and tidal forcing as well as river flux into the domain. The iterative hydrodynamic-wave model coupling is captured through the following approach. First, radiation stress gradients, determined from the SWAN wave field, serve as a surface stress forcing for ADCIRC. Elevations and currents, computed from ADCIRC, are subsequently input into the SWAN model at each iteration. The surface stress is then recalculated using the new wave field. Between these iterations the ADCIRC model is run for some appropriately small time interval during which the wave field is held constant.