Thesis (Ph. D.)--Murdoch University, 1990. / Thesis submitted to the School of Humanities. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, 1918. / "Private edition, distributed by the University of Chicago libraries." "References": p. 13. Also available on the Internet.

Thesis (Ph. D.)--University of Chicago, 1918. / "Private edition, distributed by the University of Chicago libraries." eContent provider-neutral record in process. Description based on print version record. "References": p. 13.

Stuttgart, Univ., Studienarb., 2003.

Stuttgart, Univ., Diplomarbeit, 2006.

Thesis (Ph. D.)--University of Chicago, 1918. / "Private edition, distributed by the University of Chicago libraries." "References": p. 13.

No description available.

LD2668 .T4 1947 H37 / Master of Science

No description available.

This thesis aims to address two key issues in two-dimensional (2D) convective turbulence: particle dispersion and statistics of the small-scale turbulence. / Particle dispersion plays a key role in understanding transport and mixing in turbulence, which is also significant to natural processes such as pollutants spreading in the atmosphere. To study particle dispersion in 2D convective turbulence, we use particle tracking velocimetry (PTV) technique in a soap film. The Taylor-scale Reynolds number of the system is Rλ ≈ 155. It is found that the particle dispersion law strongly depends on the initial separation. In the present system, mean square separations of particle pairs with initial separation in the inertial range grow exponentially and the ones with initial separation close to Kolmogorov length scale follow Richardson scaling law for a short range, which is consistent with the measurement in three-dimensional (3D) case and numerical result. We attribute exponential growth to the fact that the size of thermal plumes, which is regarded as energy injection scale in the present system, is comparable to the integral length scale of the flow, thus, only enstrophy cascading range is achieved for large initial separations, where exponential growth was predicted theoretically. The probability density functions (PDFs) of separation for particle pairs with initial separation close to Kolmogorov length scale display stretched exponential decay and the ones with initial separation in the inertial range exhibit exponential decay. On the other hand, for the particle pairs with initial separation near the integral length scale, Gaussian PDF is observed. The correlation of separation is also found to be initial separation dependent. The single-particle dispersion follow Taylor’s prediction. The acceleration PDF measured in the whole field deviates significantly from Gaussian distribution and displays extreme intermittency, with fluctuations racing up to 60 times of the root-mean-square values. / 本論文主要研究二維湍流熱對流中的兩個問題：粒子擴散和小尺度湍流的統計特性。 / 粒子擴散不僅對湍流運輸和混合特性的理解至關重要，而且在自然過程，如大氣污染物粒子擴散中扮演重要角色。我們通過粒子示蹤測速的方法，在薄膜中研究了二維湍流熱對流粒子的擴散。該係統對應的泰勒微尺度雷諾數是Rλ ≈ 155。研究發現，當粒子對的初始相對分離落在慣性區時，分離以指數形式增長；而當初始分離接近於Kolmogorov長度尺度時，分離在短時間以Richardson標度律演變，該發現和三維實驗結果以及數值模擬結果一致。分析表明，指數增長是由於粒子被困在相幹結構中，如熱羽流，其尺度與湍流積分長度尺度相當。我們認為，該係統中能量注入尺度即為熱羽流之尺度。這樣，只有渦量級串區在該系統中實現，理論上，可以觀察到分離的指數增長。該研究發現對於解釋污染物顆粒在大氣中長時間聚集有重要意義。研究亦表明，分離尺度接近於耗散區時，分離的概率密度函數以廣義指數形式衰減；落在慣性區時，其概率密度函數以指數形式衰減；接近於積分長度尺度時，以高斯形式衰減。研究表明，分離的相關性也依賴於初始分離。研究表明，單粒子擴散遵循泰勒擴散理論。實驗表明，全場加速度的概率密度函數不同於高斯分佈，並且體現出強間歇性和波動，加速度的波動可以達到特征速度的60倍。 / Li, Xiangyu = 薄膜中二維湍流熱對流實驗研究 / 李翔宇. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 42-45). / Abstracts also in Chinese. / Title from PDF title page (viewed on 12, October, 2016). / Li, Xiangyu = Bo mo zhong er wei tuan liu re dui liu shi yan yan jiu / Li Xiangyu. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.