本研究應用質點影像測速儀 (Particle Image Velocimetry, PIV) 於水槽中量測波浪通過4個矩形系列潛堤周遭之波流場，探討波浪作用下布拉格共振(Bragg Resonance) 效應於系列潛堤離岸端與向岸端，潛堤周遭之流場、渦流量與波浪動能之變化。研究結果顯示，第一潛堤向岸側在共振條件時，水平流速較未共振條件大，並誘發範圍較大且流速強烈的逆時鐘渦流與其對偶的順時鐘渦流，而堤頂亦有範圍與流速較未共振條件大之順時鐘渦流。在共振與非共振條件下，第四潛堤之流速與渦流均較第一潛堤小，又以共振條件時差異最明顯。在共振條件時，第四潛堤離岸側堤側渦流因未受駐波影響，而較第一潛堤離岸側堤側渦流大。
由渦流量計算結果可知，第一潛堤向岸側在共振條件下因生成較大的渦流，渦流量大於未共振條件，但在第一潛堤離岸側，共振條件下之渦流量則比非共振條件時小。第四潛堤向、離岸側之最大渦流量都較第一潛堤小。由動能分析結果顯示，堤側部分動能轉移至堤頂而形成堤頂渦流。共振條件下第一潛堤之動能明顯的大於非共振條件之動能。第四潛堤在共振條件下之動能因波浪大量反射明顯比第一潛堤小，非共振條件之動能則略小於第一潛堤。

The Bragg resonance of water waves propagation over four rectangular submerged breakwaters has been studied experimentally. The Particle Image Velocimetry (PIV) is used to measured the velocity field in the vicinity of the obstacles. The mechanism of vortex evolution and its influence on the interaction of water waves and submerged structures for both resonance and non-resonance cases is studies. The results shows that Bragg resonance induce the higher speed flow and larger vortex in the lee side of the 1st breakwater and the lower speed flow and smaller vortex in the weather side.
Vortex circulation and kinetic energy in the vicinity of the 1st and 4th breakwaters are also calculated from the measured velocities. It is found that Bragg resonance induce larger circulation and kinetic energy in the lee side of the first breakwater then non-resonance cases. But in the weather side of the first breakwater, circulation and kinetic energy of resonance cases are smaller then that of non-resonance cases. The results of the 4th breakwater are smaller then the 1st breakwater. At the same time, the results of kinetic energy shows that the partial energy is transferred from diminished vortices to new formed vortices.

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