2015-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/697700摘要：異重流又名為密度流，主要成因於密度差異造成流體環境的改變。密度變化的因素有許多，流體溫度的變化、溶解或懸浮的物質如鹽及泥砂，皆會造成密度的變化而形成流動現象。文獻中，異重流的研究絕大多數為針對平面異重流的探討，對於柱型異重流少有研究。在無側向侷限環境中，異重流向四圍擴散，此流動形態又稱為柱型異重流，有別於側向受侷限之平面異重流。在物理海洋及地質流體力學中，柱型異重流常受到科氏力的影響，其所展現之運動特性截然不同於無科氏力之平面異重流與柱型異重流。 本計畫提出使用直接數值模擬來研究柱型異重流在科氏力影響下的運動行為。在物理海洋及地質流體力學中，受科氏力影響之異重流為一具有相當代表性的問題。文獻中，此問題的研究方法僅限於旋轉水槽實驗以及淺水方程式模型，許多細微的流場特徵結構並無法量測辨識。本研究計畫將開發配合研究此問題之高精度直接數值模擬程式，此成果將為目前學界最具代表性的突破。此直接數模程式可提供許多旋轉水槽實驗無法提供之詳細資訊，這些細部資訊不僅可幫助釐清異重流在旋轉系統中的特性，更可以新的能量傳遞觀點來瞭解此問題。 本計畫之成果預期將提升國內此領域之科學研究在國際上的知名度，並培養一位博士後研究員，未來可長期致力於此領域之研究發展，為提升國家競爭力及為國內相關研究及教育繼續貢獻心力。 <br> Abstract: Gravity currents, also known as density currents, are flows driven by a density difference. The density difference can be attributed to a number of reasons: temperature differential and dissolved or suspended materials. In the literature, most of the research has been focused on the planar gravity currents, in which the gravity currents are confined by the side walls, and less attention has been focused on cylindrical gravity currents, in which the gravity currents spread radially without confinement. In physical oceanography and geological fluid dynamics, the cylindrical gravity currents are oftentimes influenced by the Coriolis forces. It is known that cylindrical gravity currents under the influence of Coriolis forces are distinctively different from those without the Coriolis forces. It is proposed in this project to investigate the cylindrical gravity currents in a rotating system using direct numerical simulations. This problem, i.e. cylindrical gravity currents in a rotating system, is a classic one in physical oceanography and geological fluid dynamics. In the literature, this problem has been investigated experimentally using a rotating tank and theoretically using shallow-water equations. However, much of the detailed information on the flow characteristics is missing because it is very difficult to obtain experimentally in a rotating tank. With the current technology, it is now possible to use direct numerical simulations to investigate this problem, to give detailed flow information and to offer a new perspective in understanding the dynamics of gravity currents in a rotating system. The outcome of proposed project will promote the international visibility of the group’s research and prepare a postdoctoral researcher for continuously conducting research in this field of study. It is also expected that the prepared researcher will devote himself in scientific research and education in the country and the benefits to the society will be long term.異重流科氏力直接數值模擬Gravity currentsCoriolis forcesDirect numerical simulation