https://scholars.lib.ntu.edu.tw/handle/123456789/81373
Title: | 颱風重點研究-子計畫五:
颱風軸對稱化動力及眼牆結構之水工模擬 Laboratory simulations on the axisymmetrization dynamics and eyewall structure of typhoons |
Authors: | 朱錦洲 | Keywords: | 渦漩合併;總渦焓量;粒子影像;測速儀;vortex merger;total enstrophy;particle image velocimetry (PIV) | Issue Date: | 31-Jul-2004 | Publisher: | 臺北市:國立臺灣大學應用力學研究所 | Abstract: | 本年度計畫吾人成功的以水工模擬及應用 二維PIV 技術探討不具背景渦度下雙渦漩 交互作用的流場物理。渦漩產生方法係利 用兩對稱之二維機翼平板之同步拖動及定 角度之轉動,帶動機翼尖端之渦漩;本研 究控制兩對稱位置產生之渦漩其相對位 置、強度為一定值時,可有系統的探討兩 等強度渦漩及不等強度渦漩交互作用的流 場演變。在定量量測方面係利用PIV 量測 技術可得到整體渦漩流場之速度與渦度分 佈時序變化。同時利用所獲得之流場資訊 計算出環流量、渦焓等物理量之逐時變 化。無論在等強度與不等強度渦漩合併的 流場中,渦漩整體的環流量皆呈現緩慢的 衰退。而總渦焓量的變化則顯示更進一步 渦漩交互作用特性,其結果可劃分成三個 階段:一、在雙渦漩互繞(orbiting)時其渦 焓量急速衰減;二、在合併(during-merging) 階段則衰減趨於平緩;三、當合併成單一 渦漩後(after-merging),渦焓量之衰減又逐 漸加劇。相關的流場現象可作為進一步了 解颱風軸對稱化及眼牆動力機制的理論及 物理模型。 In the present study, we experimentally investigate related flow physics of the interaction between two co-rotating columnar vortices in a rectangular water tank without background rotation. Using a 2-D PIV technique, we can quantitatively obtain the time evolutions of the velocity and the vorticity distributions as well as the circulation and the total enstrophy of the co-rotating vortices system. The results show a slowly decaying tendency of the total circulation of the vortices system both in the cases of the equal-strength vortices and the unequal-strength vortices interactions. We conclude three stages of the interacting process of these cases. They are (1) the orbiting process which has a rapid decrease of their total enstrophy, (2) the during-merging process which has a gentle decreasing rate of the total enstrophy and finally (3) the after-merging process which the decreasing rate of total enstrophy becomes strong again. Such flow analysis can be used as an indicator of the vortex dynamics of the co-rotating vortices system, such as the process of the axisymmetrization of typhoons and the mechanism of eyewall dynamics. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/29691 | Other Identifiers: | 922119M002010AP1 | Rights: | 國立臺灣大學應用力學研究所 |
Appears in Collections: | 應用力學研究所 |
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922119M002010AP1.pdf | 426.04 kB | Adobe PDF | View/Open |
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