An integrated physical-numerical study of groins.

摘要

The effects of groins on nearshore waves, currents and beach morphology were studied by an integrated physical and numerical modeling approach.;Both mobile and fixed bed hydraulic models were used in the physical experiments. The mobile bed tests provided a data base to be used for the calibration and verification of a numerical morphology model. Detail wave and current measurements were carried out in the fixed bed tests to acquire a clear picture of nearshore hydrodynamic conditions in the presence of groins. The fixed and mobile bed tests were conducted under similar conditions so that one could correlate their results and obtain a detail view on the behaviour of groins.;A numerical model was developed to simulate the effects of groins on nearshore waves and wave-induced currents. The model is composed of two main modules; a wave module and a current module. The wave module simulates refraction, diffraction, wave breaking, energy dissipation in the surfzone and the effects of ambient currents on waves. The current module solves the depth-integrated time-averaged equations of the conservation of mass and momentum in two horizontal dimensions. The effects of groins are implemented in both of these modules as internal boundary conditions. This numerical model can be applied to a wide variety of coastal problems (other than the study of groins) such as: wave propagation, interaction of waves with tidal and river flows, etc. Variable grid size formulation was applied in order to increase the efficiency of the model in the simulation of large coastal areas. The model can be applied to irregular shorelines and the effects of coastal flooding caused by wave setup is considered. The model is designed to be integrated into a more comprehensive morphology model, which is a task remained for a future study.;The numerical model was calibrated and verified against the data obtained from the physical experiments. The significance of wave-current interaction in the presence of groins was clearly demonstrated in these simulations.