Experimental and Numerical Studies on Wave Transformation over Artificial Reefs

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Project title

Code/計畫編號

NSC96-2221-E127-006-MY3

Translated Name/計畫中文名

波浪通過人工潛礁變形實驗量測與數值模擬

Project Coordinator/計畫主持人

Tai-Wen Hsu

Co-Investigator(s)/共同執行人

歐善惠
許泰文

Website

https://www.grb.gov.tw/search/planDetail?id=1616283

Year

2008

Start date/計畫起

01-09-2008

Expected Completion/計畫迄

01-07-2009

Bugetid/研究經費

474千元

本計畫擬利用模型試驗及數值模式求解波浪通過人工潛礁之波流場變化情形，進而探討波浪通過人工潛礁後之碎波現象。試驗擬在二維波浪斷面水槽，利用質點影像測速儀 (Particle Image Velocimetry, PIV) 及氣泡影像測速儀 (Bubble Image Velocimetry, BIV) 研究規則波浪通過人工潛礁，結構物附近之流場與波形變化，研究渦流生成及其特性，分析渦流與波能消減之關係，並進一步探討波浪通過結構物碎波後之波流場變化及能量消散。根據試驗結果，本研究擬擴充 Hsu 等人 (2004) 之雷諾平均納維爾-斯托克斯 (Reynolds Averaged Naiver-Stokes, RANS) 方程式之紊流數值模式，自行發展一完整之數值模式，藉以探討波浪和人工潛礁互制時，液面的變化及內部流場的運動特性。數值模式採用有限體積法，求解雷諾平均 Navier-Stokes 方程式，以期能夠呈現波浪場中非線性與黏性效應的影響，同時配合 k . ε 紊流模式來模擬紊流效應。其中時間差分項以顯式法 (explicit) 來離散，壓力場則藉著預測-修正方式 (predictor-corrector procedure) 來建立，配合交錯網格系統，採用不等間距網格，自由液面採水面校正法 (Level Set, LS)，以模擬波浪之變形。本模式與傳統方法之最大不同係使用 RANS 模擬波浪與人工潛礁互制，並探討波浪碎波之模擬，完整地考慮非線性、黏性和紊流效應，以展現流場的變化。 Within the framework of the present proposal, extensive two- and three-dimensional simulations of Reynolds averaged Navier-Stokes (RANS) equations and simultaneous experimental measurements using PIV/BIV (particle/bubble image velocimitry) are intended to be performed in order to gain significant insight into various complex flow phenomena surrounding an artificial reef owing to its interaction with an oncoming wave. Nonlinear effects in the nearfield of the structures such as vortex formation, turbulence and wave overtopping/breaking are intended to be investigated in a greater detail. In the numerical modeling, the transient evolution of the free-surface is opted to be captured by suitably incorporating a hybrid Level Set (LS) method in combination with the higher order weighted essentially non-oscillatory schemes. Capillary effects will be taken into account, so as to include concentrated nonisotropic stresses near the interface. Results concerning time evolution of the water-air interface and velocity field are intended to be extracted for short waves, revealing how an initial steep wave undergoes breaking and successive splash-up cycles. Breaking processes, including overturning, splash-up and air entrainment, and breaking induced vortex-like motion and the associated energy dissipation are opted to be investigated.

Keyword(s)

質點影像測速儀
氣泡影像測速儀
雷諾平均納維爾-斯托克斯
流體體積法
水面校正法
人工潛礁
PIV
BIV
RANS
VOF
level set
artificial reefs

DSpace CRIS

Experimental and Numerical Studies on Wave Transformation over Artificial Reefs

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