Studies of Finite Amplitude Shear Wave Instabilities.

摘要

LONG-TERM GOALS. My long-term goal is to develop numerical codes which are applicable to the full range of low-frequency surfzone motions, to test and refine these codes using results from field measurement programs, and to apply these codes to the prediction and characterization of fluid motions and resulting sediment transport and evolution of beach morphology. OBJECTIVES. The scientific objective of this study is to gain an understanding of various features of the low frequency nearshore current climate, including: 1. The long term evolution and dynamics of shear waves. 2. The effect of interaction and competition between several unstable wavenumber modes of finite amplitude shear waves. 3. The dynamics of edge waves in an environment where the underlying longshore current structure is strongly modified by the presence of shear waves. 4. The effect of organized forcing of the shear waves by the incident waves. The motions being studied can provide a sizeable portion of the total energy content in inner surfzone motions, and thus have a (presently not understood) impact on sediment transport and the evolution of beach morphology. We seek to eventually address these issues using the information about the hydrodynamic environment obtained from the present study.