亞重力波在不規則波入射衍生方面並沒有太多的研究，由各種不同頻率合成產生的不規則波，其衍生之亞重力波波高演化的特性亦不同於一般規則波的結果，本研究於1：10斜坡之上探討不規則波入射衍生亞重力波。實驗於國立成功大學水工試驗所大型斷面水槽進行，在水槽中放置93支電容式波高計及3支溯升計用以得到波浪演化時高空間解析的資訊，並以JONSWAP波譜作為入射條件，配合改變入射波高，對其生成之亞重力波能量、波高成長趨勢進一步的探討，以對此現象作進一步的解釋。
由前人研究中可得知坡度越陡對亞重力波的影響會造成自由長波主導的現象，吾人將亞重力波拆成入射波及反射波的部份，發現到其自由長波波高皆高於限制長波。進一步將分析亞重力波內各成份波之成長情形，其波浪成長趨勢皆以Green’s Law描述方式演化，而由無因次底坡度參數值介在0.614到11.67之間，皆顯示出移動碎波點機制作用明顯之證據。

The evolution of infragravity energy of random waves over a 1/10 uniform sloping each was carried out by analyzing the experimental data conducted in a super wave tank with length of 300 meter, width of 5 meter, and depth of 5.2 meter at Tainan Hydraulics Laboratory (THL). To obtain a high spatial resolution of surface elevation, a total of 96 wave gauges were installed along the wave tank. In addition, the JONSWAP spectrum was used in the experiments. The components of infragravity waves were separated through multi-step method proposed by Battjes et al. (2004). Based on our results, it is found that the magnitude of free waves (reflected wave) was always larger than that of bound waves except at the locations near the shoreline. Additionally, the components of different frequency band of infragaravity show the amplitude growth according to Green’s Law during the shoaling process. Experimental data show that the generation of infragravity waves is mainly contributed by moving breakpoint mechanism.

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