Analytical Study of Wave Damping by Emergent and Floating Flexible (II)

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Project title

Code/計畫編號

MOST107-2221-E019-013

Translated Name/計畫中文名

一般及浮式離岸柔性植被對波浪減衰之研究(II)

Project Coordinator/計畫主持人

Yuan-Jyh Lan

Funding Organization/主管機關

National Science and Technology Center for Disaster Reduction

Department/Unit

Center Experimental Ocean Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=12676600

Year

2018

Start date/計畫起

01-08-2018

Expected Completion/計畫迄

31-07-2019

Bugetid/研究經費

716千元

ResearchField/研究領域

土木水利工程

本計畫擬針對波浪與離岸水生植被互相作用問題進行研究，以瞭解波浪受到水生植被阻尼效應影響下之波浪減衰。波浪運動採用線性波浪理論；離岸水生植被場域視為一柔性透水系統。以 Lan and Lee (2000) 透水彈性體理論為基礎，引入植被元素之摩擦係數，建立波浪通過水生植被系統互相作用之理論，在週期性運動假設下，推導出適合本計畫問題之控制方程式，並配合植被柔性透水體交界面應力、應變、流體壓力與通率連續之邊界條件求解析解，建立數值解析模式。研究將觸及以往學者較少研究之出水植被自由水面邊界波動變化問題的處理。數值解析模式建立完成後，將根據所蒐集之相關研究文獻，研討可供驗證之資料的完整度，進行波浪通過離岸水生植被之二維斷面試驗，補充不足之驗證資料，試驗結果並將與理論解析結果相互驗證比較。驗證解析解之合理性後，將分析波浪通過離岸水生植被時，水生植被之莖密度、空間覆蓋、柔軟性等效應改變以及波浪條件改變的情形下，波浪反射與透過的變化。計畫以兩年的時間進行研究，本年度為第二年計畫，將以第一年計畫(MOST 106-2221-E-019-034)所推導之出水透水彈性體理論為基礎，針對浮式植物群進行研究。研究成果將可進一步瞭解波浪通過離岸出水植被以及浮式植物群互相作用之運動與動力機制，與波浪減衰影響，提供海洋環境保護及生態工程設計之參考。 In this study, the problem of periodic waves interaction with offshore aquatic vegetation is investigated. Water waves are described using the linear wave theory. The offshore aquatic vegetation field is considered as a flexible permeable system. Based on the modified poro-elastic medium theory presented by Lan and Lee (2000) and referring to the friction coefficient of vegetation elements, the governing equations for the study are derived. Continuity of stress, strain, dynamic fluid pressure and flow flux at the interfacial surface are used to solve the problem. This study deals with the free surface boundary condition in the field of emergent vegetation that previous studies have paid less attention. After establishing the numerical analysis model, the completeness of the data available for validation will be examined based on the relevant literatures. The experimental study will be performed to supplement the validation data. The analytical results of present study could be compared with the experimental results. Using the present analytic solution, effects of plant characteristics (stem density, spatial coverage, softness/stiffness) of offshore aquatic vegetation on wave reflection and transmission are studied. The project will be completed in two years and this year is the second year, for studying the floating vegetation based on the emergent poro-elastic medium theory developed in the first year (project number: MOST 106-2221-E-019-034). The research will further understand the kinetic and dynamic mechanisms on the interaction of waves and offshore aquatic vegetation as well as the influence of wave damping. The results will provide references for marine environmental protection and ecological engineering.

Keyword(s)

波浪減衰
出水植被
浮式植物群
透水彈性體
互相作用
wave damping
emergent vegetation
floating vegetation
poro-elastic medium
interaction.

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Analytical Study of Wave Damping by Emergent and Floating Flexible (II)

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