https://scholars.lib.ntu.edu.tw/handle/123456789/161993
標題: | 沙床形之三維多顆粒泥砂躍移研究 | 作者: | 李鴻源 | 關鍵字: | 推移載;躍移;碰撞機制;三維動態影像數位化系統;沙丘;Bed load;Saltation;3-D flow visualization technique;Dune | 公開日期: | 2004 | 出版社: | 臺北市:國立臺灣大學水工試驗所 | 摘要: | 以往研究的成果,主要是針對二維泥砂顆粒與底床顆粒的碰撞行為以及泥砂顆粒的運動型態作探討(Garcia and Nino(1994,1998)、陳彥旭(1998)、游景雲(1999)),已獲得不錯之成果。在有關三維泥砂運行與躍移之研究,本研究群(林穎典(2000)、李博甯(2001)、王筱雯(2002)),均假設底床為規則顆粒組成之平坦床形,建立一包含底床碰撞與空間碰撞之三維多顆粒連續躍移數值模式,藉此模式探討顆粒躍移之運動特性。然而一般明渠中,底床床型會依流速的不同而呈現包括平整(flat bed)、沙纹(ripple)、沙丘(dune)、沙浪(antidune)及急灘 與深潭(chutes and pools)等不同型式,不同型式的床型會對近床區域的流況造成影響,進而影響到推移載顆粒的運動情形。本研究針對沙丘(dune) 底床型態的三維泥砂顆粒躍移行為及其間的碰撞機制進行探討,藉助三維動態影像數位化系統來建立一套在沙丘底床型態下之三維多顆粒連續躍移模式,並和過去所 發展相互比較,希望能對泥砂顆粒躍移運動有更進一步的了解。 A series of studies regarding the two dimensional collision mechanism with the channel bed and among the saltating particles were conducted by Garcia and Nino (1994, 1998) and our group (Chen 1998, You, 1999). The simulation results are satisfactory. For past years, our group (Lin 2000, Lee, 2001, Wang, 2002) had extended the experiments to three dimensional conditions. The bed forms of our previous experiments were flat bed and formed by uniformly distributed sediment particles. However, the bed forms in natural rivers vary with different flow conditions. Different types of bed forms, were observed, namely, flat bed, ripple, dune, antidune, and chutes and pools. Particles saltation characteristics will definitely be different under bed forms. The purpose of this study is to investigate the three dimensional saltation characteristics on a dune bed, with special attention on the collision behaviors between the saltating particles and the channel bed and interparticle collision behaviors. A three dimensional flow visualization technique will be modified and upgraded in this study to measure the three dimensional saltation trajectories on a dune bed. Basing on these data, a three dimensional continuous saltation for multiple sediment particles will then be developed. This model will be very helpful in the study of bed load transport. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/9921 | 其他識別: | 922211E002039 | Rights: | 國立臺灣大學水工試驗所 |
顯示於: | 生農、工學院附設水工試驗所 |
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922211E002039.pdf | 280.27 kB | Adobe PDF | 檢視/開啟 |
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