Experimental and numerical investigations of floating breakwater performance.

摘要

The main objective of the current study is to investigate the hydrodynamic interaction of small scale waves with floating breakwaters, experimentally and numerically. The breakwater models considered here are single or multiple cylindrical sections with different mooring configurations.;For the model studies a wave flume with a flap-type wave generator and a progressive wave absorber was designed, constructed, and used to investigate the wave transmission characteristics of multiple breakwater configurations for regular waves in deep and transitional water depths. The test results show that wave attenuation is achieved primarily by reflection when the models were fully restrained. Hence, the efficiency of the floating breakwater is strongly dependent on the draft and the freeboard of the breakwater. For partially restrained models, dissipation also becomes significant. It was also observed that horizontal restraint is superior to vertical restraint in terms of improving breakwater efficiency. A floating breakwater made of polyethylene irrigation tubing was subjected to a short-term prototype-scale field test. In the field test, wave amplitudes were reduced by an average of approximately 60%. It is concluded from both the model and the field studies that cylindrical pipes can be used effectively as floating breakwaters for small lakes and reservoirs.;A two-dimensional vertical numerical wave tank was designed using a commercially available CFD software package, to further investigate the interaction of the waves with cylindrical floating breakwaters. A new method to generate waves by using a mass source function was developed and coded into the numerical model. The new wave generation method was tested with linear monochromatic waves and irregular waves and compared with the experimental data. It is shown that the new method can successfully be used to generate a wide range of deep and intermediate wave conditions in numerical wave tanks. The numerical model used to examine the effect of overtopping and breakwater restraint. The results are validated with the experimental measurements and the field data. It is shown that modified numerical model can efficiently be used to simulate the interaction of linear monochromatic and irregular waves with floating breakwaters even in case of overtopping.