2008-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/654649摘要：本計畫接連前年所提、正在執行的計畫，期能獲得足夠時間作一有深度的探究，無論在實驗及數理分析。目前已發展的技術，使我們在高韋伯數區域對雙液滴及液滴液面之碰撞發現新的現象，有助基礎流體力學的探討並應用至相關工程與科學領域。在本計畫中，除繼續利用此技術作更深研究，我們亦將設計不同於前的液滴產生技術，例如利用周圍強氣流帶動已生成的液滴，目前已有初步成果。一旦實驗技術成熟，我們即可探討更高韋伯數的液滴碰撞現象，可藉此模擬不易實驗的環境如近臨界點的碰撞機制，常見於航太推進系統中高溫高壓的燃燒室。另一發展重點為數值分析方法，傳統方法著重於巨觀尺度參數的模擬，然而我們之前研究顯示，當液面相互接近時，微小尺度的結構是由不同物理機制所主導，如稀薄氣體效應與分子吸引力，須結合不同的數值計算才可準確預測regime diagram的轉變臨界。因此我們將針對數值模擬，發展可以進階分析液滴撞擊的方法。初步構想為整合既有理論和數值模型，如將Maxwell的滑動邊界用於front-tracking method，以加入稀薄氣體效應；並將Hamaker的理論與計算模型作適當處理，以模擬van der Waals分子鍵結力。另一目標為晶格波茲曼方法，我們將以先前建立的程式，繼續發展可定量解析多相流體尤其是液滴間結合機制的技術。<br> Abstract: The project is proposed as a continuation of our last one that was planned for three years but only one year has been approved. Following the initial schedule, we have been developing and testing various techniques to generate high-speed droplets, and investigating the underlying physics for the collision dynamics between two droplets and between a droplet and a wet/dry surface. The current interest is in the regime of high Weber number which can simulate the dynamics of deformable interfaces at near critical condition in combustion chambers specifically relevant to aerospace applications in environment of high pressure and temperature that is not readily reached by experiment. By means of a cutting technique developed recently, we have found a new regime of binary droplet collision and identified the transition boundaries for various breakup mechanisms that shed light on the fundamental structure of droplet dynamics and further application to industrial purposes. To fully accomplish our goal, we propose to continue our present experimental technique for more detailed measurement while developing also new methods for creating droplets that can attain higher range of Weber number. In addition to experimental studies, we have been developing numerical methods based on the immersed-boundary method and lattice Boltzmann method for quantitatively analyzing the complex transition structure.液滴碰撞多相流面追蹤法高速液滴晶格波茲曼方法droplet collisionmultiphase flowfront-tracking methodhigh-velocity dropletlattice Boltzmann method