波浪通過不透水潛堤之流場實驗研究

Flow Fields of Water Waves Propagating over An Impermeable Submerged Rectangular Obstacle:An Experimental Investigation

許展豪(Chan-Hao Hsu)

指導教授 ： 林銘崇 ； 丁肇隆

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.00181

摘要

本文利用粒子影像測速儀(P.I.V.)並搭配影像接圖之技巧，研究當波浪通過矩形潛堤時，由於波浪與潛堤持續之交互作用下，因非線性增強致使波浪逐漸產生變形，並導致高階諧和波之生成，造成潛堤週遭流場所產生之變化。而本研究則僅著重於針對實驗結果所呈現物理現象之變化情況，作一定性上之探討。其中包含速度向量場之分析、堤角渦流場之分析與粒子運動軌跡型態等三類。從結果中可以看出，通過空間上不同位置上方產生之分離小波，其能量大小與相對位置，會影響速度向量場之變化，當分離小波通過時，會使得流場粒子運動產生類似短暫停滯的行為，因而造成速度值有減小的現象。本文亦將波形與流場同步顯像，以更清楚地呈現兩者間交互作用之關聯性。潛堤後堤角上方之波形變化，將會導致渦流的運動行為產生有趣的現象，而堤後之渦流行為與運動程度，皆較堤前來得成熟且劇烈。空間上粒子運動軌跡之演化型態，則與通過其上方之波形變化呈現一對一對映的關係。

關鍵字

粒子影像測速儀 ； 潛堤 ； 高階諧和波 ； 渦流 ； 粒子運動軌跡

並列摘要

Surface waves propagating over a impermeable submerged rectangular breakwater were investigated in this research. The effect of nonlinearity due to waves encountering the breakwaters will induce wave deformations as well as the generations of super harmonics. A PIV measurement system was used to record the particle motion in fluids, such that the wave flow field can be analyzed. Based on the measured results, qualitative descriptions of the variations of flow fields, vortex generations around breakwater corners and particle trajectories were made in this research. It showed that the velocity fields were different in front of, above and behind the breakwaters. The amplitude and the relative position of super harmonic waves affect velocity fields significantly. The vortex generation at the back corner is more mature and more severe than the vortex generated at the front corner. From the results, periodic motions of vortex generations were seen clearly. The particle trajectories were also different at different spaces. From our results, the evolution of particle trajectories were presented in this research.

並列關鍵字

PIV measurement system ； submerged breakwater ； super harmonic generation ； vortex generation ； particle trajectory

參考文獻

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