Mak Chung Ming = 多孔介質中的局部性與整體性漲落 / 麥仲明. / Thesis submitted in: July 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 116-123). / Text in English; abstracts in English and Chinese. / Mak Chung Ming = Duo kong jie zhi zhong de ju bu xing yu zheng ti xing zhang luo / Mai Zhongming. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.ii / Acknowledgements --- p.iii / Table of Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.ix / Chapters / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Motivation of research on porous medium --- p.1 / Chapter 1.2 --- Description of porous medium --- p.2 / Chapter 1.3 --- Brief history of research of thermal convection in porous medium --- p.5 / Chapter 2. --- Background --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Governing equations and parameters --- p.8 / Chapter 2.3 --- Review of literature --- p.15 / Chapter 2.4 --- Summary --- p.20 / Chapter 3. --- Instrumentation --- p.21 / Chapter 3.1 --- Experimental setup --- p.21 / Chapter 3.1.1 --- Porous medium --- p.21 / Chapter 3.1.2 --- Working fluid --- p.24 / Chapter 3.1.3 --- Container cell --- p.25 / Chapter 3.1.4 --- Top plate --- p.26 / Chapter 3.1.5 --- Bottom plate --- p.28 / Chapter 3.2 --- Thermistors and its calibration --- p.28 / Chapter 3.3 --- Other apparatuses --- p.31 / Chapter 4. --- Data analysis and results --- p.33 / Chapter 4.1 --- Measurement of global heat flux --- p.33 / Chapter 4.1.1 --- Heat transfer characteristic --- p.34 / Chapter 4.2 --- Local temperature measurements --- p.37 / Chapter 4.2.1 --- 3mm bead´ؤwater system (small cell) --- p.38 / Chapter 4.2.2 --- 6mm bead´ؤwater system (small cell) --- p.44 / Chapter 4.2.3 --- 6mm bead´ؤwater system (large cell) --- p.64 / Chapter 4.2.4 --- 10mm bead´ؤwater system (large cell) --- p.76 / Chapter 4.3 --- Correlation of the time series --- p.96 / Chapter 4.4 --- Thermal pulse experiment --- p.101 / Chapter 5. --- Conclusions --- p.111 / Appendix --- p.114 / Bibliography --- p.116

Lau Chun Keung = 受調諧下溫度湍流的實驗研究 / 劉振強. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 86-88). / Text in English; abstracts in English and Chinese. / Lau Chun Keung = Shou diao xie xia wen du tuan liu de shi yan yan jiu / Liu Zhenqiang. / Chapter 1 --- Acknowledgments --- p.iii / Chapter 2 --- Introduction --- p.1 / Chapter 2.1 --- Pulsating flow --- p.1 / Chapter 2.2 --- Rayleigh Bernard Convection: Equations and Parameters --- p.5 / Chapter 2.3 --- Rayleigh Benard Convection: Physical Picture --- p.7 / Chapter 2.4 --- Previous work on Turbulent Convection --- p.10 / Chapter 2.5 --- Motivation --- p.11 / Chapter 3 --- Experimental Setup --- p.13 / Chapter 3.1 --- The Convection cell --- p.13 / Chapter 3.2 --- Heating and Cooling --- p.18 / Chapter 3.3 --- Temperature and Voltage measurement --- p.20 / Chapter 3.3.1 --- Temperature Probes --- p.20 / Chapter 3.3.2 --- "Data, acquisition: Multimeters and Lock-In" --- p.22 / Chapter 4 --- Experimental Results --- p.27 / Chapter 4.1 --- Steady State Convection --- p.27 / Chapter 4.1.1 --- Experimental parameters and its determination --- p.27 / Chapter 4.1.2 --- Fluctuations at various locat ion of cell --- p.28 / Chapter 4.1.3 --- Nusselt Number --- p.37 / Chapter 4.2 --- Modulated Convection --- p.38 / Chapter 4.2.1 --- Parameters of the system --- p.40 / Chapter 4.2.2 --- Temperature variation at the plates: general picture --- p.41 / Chapter 4.2.3 --- Temperature variation at the plates: modulatiou frequency dependence --- p.42 / Chapter 4.2.4 --- Phase differences between response and modulation --- p.58 / Chapter 4.2.5 --- Temperature Variation at the Plates: Further Exploration of Parameter Space --- p.61 / Chapter 4.2.6 --- Local Signals at Mid-Height under modulation --- p.63 / Chapter 4.2.7 --- Time lag between two probes --- p.76 / Chapter 5 --- Conclusion --- p.83 / Chapter 5.1 --- Conclusion --- p.83 / Chapter 5.2 --- Outlook for further studies --- p.85 / Bibliography --- p.86 / Thermal dissipation rate --- p.89

Zhou Sheng-qi = 高瑞利數湍流熱對流中溫度和速度場的結構和統計性質研究 / 周生启. / "December 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 134-147) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese. / Zhou Sheng-qi = Gaoruili shu tuan liu re dui liu zhong wen du he su du chang de jie gou he tong ji xing zhi yan jiu / Zhou Shengqi.

by Lui Siu Lung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 132-136). / by Lui Siu Lung. / Abstract --- p.i / Acknowledgements --- p.ii / Table of Contents --- p.iii / List of Figures --- p.v / Chapter / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- The Parameters --- p.1 / Chapter 1.2 --- The Stories of Turbulent Convection --- p.2 / Chapter 1.3 --- The Models: Plumes with no Flow or a Flow with no Plumes? --- p.3 / Chapter 1.4 --- Building up the Picture --- p.5 / Chapter 1.5 --- Starting Point of the Experiment --- p.6 / Chapter 2. --- Setup of the Experimental Environment --- p.8 / Chapter 2.1 --- The Convection Cell --- p.8 / Chapter 2.2 --- The Temperature Probe --- p.12 / Chapter 2.3 --- The Thermistors --- p.15 / Chapter 2.4 --- The Large Scale Circulation and the Plumes --- p.19 / Chapter 2.5 --- Building up the Convection --- p.22 / Chapter 3. --- Hard Turbulence Properties and Scalings in the Normal Cell --- p.27 / Chapter 3.1 --- Heat Transfer Efficiency --- p.27 / Chapter 3.2 --- Thermal Boundary Layer --- p.32 / Chapter 3.3 --- The RMS Temperature Fluctuation --- p.39 / Chapter 3.4 --- Temperature Time Series --- p.42 / Chapter 3.5 --- Histograms --- p.48 / Chapter 3.6 --- Power Spectrum --- p.53 / Chapter 3.7 --- Summary on the Normal Cell --- p.56 / Chapter 4. --- Horizontal-Position-Dependent Thermal Boundary Layer --- p.58 / Chapter 4.1 --- Orientation --- p.59 / Chapter 4.2 --- Along the Large Scale Circulation --- p.60 / Chapter 4.3 --- Perpendicular to the Large Scale Circulation --- p.70 / Chapter 4.4 --- Horizontal Measurement for the A = 2 Cell --- p.78 / Chapter 4.5 --- Summary on the Horizontal Measurement --- p.81 / Chapter 5. --- Sphere in the Cell --- p.84 / Chapter 5.1 --- Heat Transfer Efficiency --- p.84 / Chapter 5.2 --- Thermal Boundary Layer --- p.86 / Chapter 5.3 --- The RMS Temperature Fluctuation --- p.87 / Chapter 5.4 --- Temperature Time Series --- p.88 / Chapter 5.5 --- Histograms --- p.92 / Chapter 5.6 --- Summary on the Sphere Cell --- p.94 / Chapter 6. --- Fingers in the Cell --- p.96 / Chapter 6.1 --- The Gear Cell --- p.96 / Chapter 6.1.1 --- Heat Transfer Efficiency --- p.96 / Chapter 6.1.2 --- Thermal Boundary Layer --- p.98 / Chapter 6.1.3 --- Flow Pattern in the Gear Cell --- p.100 / Chapter 6.1.4 --- Temperature Time Series --- p.104 / Chapter 6.1.5 --- Histograms --- p.109 / Chapter 6.1.6 --- Power Spectrum --- p.110 / Chapter 6.2 --- The Finger Cell --- p.117 / Chapter 6.2.1 --- Heat Transfer Efficiency --- p.117 / Chapter 6.2.2 --- Temperature Time Series --- p.120 / Chapter 6.2.3 --- Histograms --- p.122 / Chapter 6.2.4 --- Power Spectrum --- p.125 / Chapter 6.3 --- Summary on the Finger Cells --- p.127 / Chapter 7. --- Conclusions --- p.129 / References --- p.132 / Appendix --- p.137

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Two thermal convection problems of geophysical interest are examined, theoretically. First, convection in the earth's mantle is treated on the basis of a one-dimensional 'strip model'. This model results from further simplification of the well known 'Rayleigh model'. For homogeneous, Newtonian fluids, the strip model yields results similar to those obtained by the Rayleigh method. The strip model is used to determine the critical Rayleigh number for convection in an internally heated two-phase fluid. The critical number depends on the parameters of the phase transition, the physical properties of the fluid, and the depth of the fluid layer. Depending on these factors, a univariant phase transformation may either enhance or hinder convective instability. For the olivine-spinel and spinel-oxides transitions in (MgFe)₂SiO₄ which are thought to take place in the upper mantle, it is shown that the critical Rayleigh number is altered only slightly from the critical number for convection in a fluid with one phase. This result holds both for convection in the entire mantle or convection restricted to the upper mantle. Hence the phase changes are of minor importance regarding the existence of mantle convection in general. A method for estimating the order of magnitude of the displacement of the phase surface as a function of Rayleigh number is outlined for a fluid with only one phase transition. The strip model is also used to treat convection in non-Newtonian fluids obeying a power law rheological equation. If the mantle is governed by a flow law of this type, it appears that convection can take place. Lastly, the procedure for applying the strip model to fluids with variable viscosity and thermal conductivity is outlined. The second convection problem concerns some aspects of convection of fluids in thin vertical fractures in the crust. A steady state model is developed to estimate the magnitude of the mass flow as a function of fracture thickness. It is shown that fractures of the order of a millimeter thick or greater can carry a measurable convective flow. A time dependent model is used to estimate the rate of decay of the mass flow with time. The results indicate that in fractures of the order of a centimeter thick, a measurable decrease of the mass flow takes place after a period of the order of a day. This rapid decay rate suggests that the principal effect of sea water convection in extensive fracture systems which are expected on mid-ocean ridge crests is to cool a volume of crustal rock in the vicinity of the fractures. Circulation of sea water in vertical fractures in the upper crust may provide an explanation of 1) the relatively low conductive heat flow measured at some locations on ocean ridge axes and 2) the very 'noisy' data obtained in the axial zone. / Graduation date: 1972

The effect of unsteady thermocapillary convection on the mass transfer rate of a solute between two immiscible liquids within a rectangular microscale channel with differentially heated sidewalls was numerically investigated. A computational fluid dynamic code in Fortran77 was developed using the finite volume method with Marker and Cell (MAC) technique to solve the governing equations. The discrete surface tracking technique was used to capture the location of the moving liquid-liquid interface. The code produced results consistent with those reported in published literature. The effect of the temperature gradients, the aspect ratio, the viscosity of liquid, and the deformation of the interface on the mass transfer rate of a solute were studied. The mass transfer rate increases with increasing temperature gradient. The improvement of the mass transfer rate by the thermocapillary convection was found to be a function of the Peclet number (Pe). At small Pe, the improvement of the mass transfer rate increases with increasing Pe. At high Pe, increasing the Pe has no significant effect on increasing the mass transfer rate. Increasing the aspect ratio of the cavity up to 1 increases the mass transfer rate. When the aspect ratio is higher than 1, the vortex moves only near the interface, resulting in decreasing the mass transfer rate. By increasing the viscosity of the liquid in top phase, the maximum tangential velocity at the interface decreases. As a result, the improvement of the mass transfer rate decreases. The deformation of the interface has no significant effect on the improvement of the mass transfer rate. By placing the heating source at the middle of the cavity, two steady vortices can be induced in a cavity. As a result, the mass transfer rate is slightly enhanced than that in the system with one vortex. By reversing the direction of the temperature gradient, the mass transfer rate decreases due to the decrease in the velocity of bulk fluid. The thermocapillary convection also promotes the overall reaction process when the top wall of the cavity is served as a catalyst. / Graduation date: 2005

Described in this thesis is an investigation of the fully developed natural convection heat transfer in a vertical channel formed by two infinitely wide parallel plates maintained at a uniform wall temperature. Closed-form solutions for the velocity and temperature profiles are developed along with local and averaged Nusselt numbers. The local Nusselt number based on bulk temperature is found to be 3.77. This result is an analog corresponding to 7.60 for fully developed laminar forced convection in a parallel plate channel with uniform wall temperature boundary condition. The local Nusselt number based on the ambient temperature is deduced as a function of flowwise location. Results are compared with existing numerical and experimental data to find good agreement. / Graduation date: 1997

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