Recent studies and future plans on wave and turbulence in nearshore environments
摘要：
The speaker’s main research results include two topics: “Laboratory observations of surf-zone dynamics and turbulence” and “field observations of wave and turbulence dissipation in a coral-reef lagoon system”. The first study focused on studying the dynamics of wave-breaking-generated turbulence under laboratory spilling waves. A particle image velocimetry was used to measure the full-field internal flow velocities under breaking waves. A high-resolution PIV system was developed to observe the viscous bottom boundary layer in the laboratory surf zone. The evolution of wave energy flux, wave dissipation rate, ensemble-averaged flows, vorticity, boundary layer thickness, bottom shear stress, turbulent quantities, transport mechanism of turbulence in the surf zone were successfully quantified and studied.The second study focused on field measurements of dissipation rates in the reef-lagoon system surrounding LEI, GBR off the coast of Queensland, Australia. Wave energy dissipation rates were measured using wave-gauge techniques, and turbulence dissipation rates were measured by inertial turbulence subrange techniques using acoustic Doppler velocimetry (ADV) data. The results showed that the dissipation of wave energy in the LEI lagoon is tidally modulated and strongly correlates with frictional dissipation due to the presence of the extremely rough bottom boundary. The observed turbulence dissipation in this wave-dominated lagoon is much larger than the recently reported values for unidirectional flows over natural fringing coral reefs, implying an enhancement of turbulence dissipation rate in wave environments. In particular, the wave dissipation rate was successfully correlated to its underlying mechanism — turbulence dissipation rate. The friction dissipation, friction factor, and dissipation induced by the in-canopy drag force of the coral heads were studied as well. In addition, an airborne LIDAR technique was used to observe the wave dissipation rate over the LEI coral reefs. The field experiments demonstrated the feasibility of using airborne LIDAR to remotely measure surface wave energy fluxes and thereby turbulent kinetic energy dissipation rates over coral reef lagoon systems. Finally, the speaker will address the future plans and other ongoing research projects that are related to the properties of wave and turbulence in nearshore environments.