An investigation was carried out into external-Coanda Effect flares designed by British Petroleum International plc. The phenomenon of interest was breakaway of an under expanded axisymmetric curved wall jet from the guiding surface due to high blowing pressure. A survey of investigations of similar flows suggested very complex jet fluid dynamics. Strong cell structure including shock waves was present giving bulk and discrete compression and bulk dilatation. More expansion was imposed by the radial velocity components. Wall curvature and a rear-facing step added further significant influences. The combination of these factors is known to produce highly non-linear turbulence, and this constitutes a major difficulty for the application of computational methods to the flare. In view of the amount of resources required to eliminate the problems of using a Navier-Stokes code, an economical approach was adopted, matching the Method of Characteristics to various simplified models and an integral boundary layer. In the experimental work, a planar model of the flare was contructed and studied using a wide range of methods in order to achieve accuracy and provide comparability with other work. An axisymmetric model was designed and investigated in a similar manner, so that the influence of this geometry could be clearly distinguished. A full-scale flare was subjected to a restricted range of tests to compare the laboratory results with the industrial application. The results from all the experiments demonstrated good correspondence. The main conclusion was that amalgamation of separation bubbles is crucial for breakaway. These are present long before breakaway, and are strongly reduced by decreasing the cell scale, adding a rear-facing step and axisymmetry, which leads to improved breakaway performance. Although the computational methods did not prove robust enough for all design purposes, they did permit significant insights into the mechanism of breakaway.

"This study examines atmospheric boundary layer over and around the Gulf of Mexico during return flow events. The locations investigated are on both the Texas coast and the Florida coast. Moreover, several inland stations such as Jackson (JAN), Mississippi and Shelby Co Airport (BMX), Alabama are added to the analyses to make some comparisons. In addition to examining the boundary layer structure of these coastal and inland stations, an attempt is made to investigate thermadynamic structure on the continental shelf of the Gulf of Mexico in terms of both synoptic analysis and model applications. Return flow events of the Gulf of Mexico are mainly examined by using a three dimensional Air Mass Transformation (AMT) model and a one-dimensional Planetary Boundary Layer (PBL) model. The models are intende for short-range weather forecasts of the temperature profiles in the lower atmosphere and the structure of the boundary layer"--Abstract. / Typescript. / "1996." / "Submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science." / Advisor: Paul H. Ruscher, Professor Directing Thesis. / Includes bibliographical references.

by Yongbao Xin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 113-117). / by Yongbao Xin. / ABSTRACT --- p.I / ACKNOWLEDGMENTS --- p.II / LIST OF FIGURES --- p.V / LIST OF TABLES --- p.VIII / CHAPTERS / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Turbulence: A Long-standing and Unsolved Problem --- p.1 / Chapter 1.2 --- Rayleigh-Benard Convection --- p.3 / Chapter 1.3 --- High Rayleigh Number Rayleigh-Benard Convection --- p.5 / Chapter 1.3.1 --- The Rayleigh number dependence of Nu --- p.6 / Chapter 1.3.2 --- Large-scale flow in RB convection --- p.7 / Chapter 1.3.3 --- Thermal plumes in the high Ra convection --- p.9 / Chapter 1.4 --- Velocity Field and Viscous Boundary Layer Measurement in Rayleigh-Benard Convection --- p.11 / Chapter 2. --- SETUP OF RAYLEIGH-BENARD CONVECTION --- p.14 / Chapter 2.1 --- The Convection Cells --- p.14 / Chapter 2.2 --- Built Up the Convection --- p.18 / Chapter 2.2.1 --- Preparations of fluid --- p.18 / Chapter 2.2.2 --- Procedures to have a stable convective state --- p.19 / Chapter 2.3 --- Measurements of the Nusselt Number --- p.22 / Chapter 3. --- VELOCITY MEASUREMENT IN RAYLEIGH-BENARD CONVECTION --- p.25 / Chapter 3.1 --- Dual-beam Incoherent Cross-correlation Spectroscopy --- p.25 / Chapter 3.1.1 --- Theory of the technique --- p.25 / Chapter 3.1.2 --- Experimental setup --- p.31 / Chapter 3.1.3 --- Calibration and applications of the technique --- p.34 / Chapter 3.1.4 --- Summary --- p.41 / Chapter 3.2 --- Velocity Measurement in Turbulent Rayleigh-Benard Convection --- p.42 / Chapter 3.2.1 --- Cross-correlation functions in turbulent convection --- p.42 / Chapter 3.2.2 --- Some experimental details --- p.43 / Chapter 3.2.3 --- Some issues to be concerned in the velocity measurement --- p.47 / Chapter 4. --- LARGE SCALE CIRCULATION IN RAYLEIGH-BENARD CONVECTION --- p.50 / Chapter 4.1 --- Large Scale Circulation in Cylindrical Cells --- p.50 / Chapter 4.1.1 --- "Large scale circulation in cells of AR =1,2，and 44" --- p.50 / Chapter 4.1.2 --- Flow pattern in AR = 0.5 cell --- p.55 / Chapter 4.1.3 --- Velocity profiles along vertical central axis --- p.57 / Chapter 4.1.4 --- Prandtl number dependence of the boundary layer properties --- p.61 / Chapter 4.2 --- Large Scale Circulation in Cubic Cell --- p.65 / Chapter 4.2.1 --- Large scale flows near the plate and near the sidewall --- p.65 / Chapter 4.2.2 --- Velocity profiles along the vertical axis --- p.68 / Chapter 4.3 --- Summary --- p.73 / Chapter 5. --- SCALING PROPERTIES OF THE BOUNDARY LAYER QUANTITIES --- p.75 / Chapter 5.1 --- Ra Dependence of Boundary Layer Properties --- p.75 / Chapter 5.1.1 --- Scaled velocity and standard deviation profiles at different Ra --- p.75 / Chapter 5.1.2 --- Scaling properties of the maximum mean velocityvm and the maximum standard deviation σm --- p.76 / Chapter 5.1.3 --- Scaling properties of the shear rate γv and the gradient of the standard deviation yσ --- p.80 / Chapter 5.1.4 --- Scaling properties of boundary layer thickness --- p.84 / Chapter 5.2 --- Aspect-ratio Dependence of Boundary Layer Properties --- p.87 / Chapter 5.2.1 --- AR dependence of vm(Ra) and σm(Ra) --- p.87 / Chapter 5.2.2 --- AR dependence of the shear rate --- p.89 / Chapter 5.2.3 --- AR dependence of the viscous boundary layer thickness --- p.89 / Chapter 5.2.4 --- Vertical motion of the coherent structures in AR = 0.5 cell --- p.92 / Chapter 5.3 --- Summary --- p.93 / Chapter 6. --- CONCLUSION --- p.96 / APPENDIX / Chapter A1. --- NUMERICAL ANALYSIS OF THE CORRELATION FUNCTION EQ. 315 --- p.100 / Chapter A1.1 --- Analysis with Gaussian PDF Distribution --- p.100 / Chapter A1.2 --- Definition and Properties of Erfc(x) --- p.101 / Chapter A1.3 --- The Variable of Erfc in Eq. 315 --- p.104 / Chapter A1.4 --- Difference of Peak Position and t0 --- p.105 / Chapter A2. --- LASER HEATING EFFECTS IN THE LIGHT SCATTERING EXPERIMENT --- p.106 / Chapter A 2.1 --- Introduction --- p.106 / Chapter A 2.2 --- Experimental Technique --- p.106 / Chapter A 2.3 --- Results and Discussion --- p.108 / Chapter A 2.4 --- Summary --- p.109 / REFERENCES --- p.113

No description available.

Bibliography: leaves 201-207. This thesis presents studies of the non-linear mass-transfer kinetics and a linear analysis of the hydrodynamic stability of systems under conditions of intense interfacial mass transfer.

Typescript (photocopy) / ix, 240 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 1978

69 leaves : tables, graphs ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 1978

The very stable boundary layer is a region of the atmosphere typified by large vertical gradients of temperature and momentum. Analysis of very stable atmospheric flows is complicated by the presence of nonlinear interactions among gravity waves, shear-driven overturning circulations, two-dimensional vortical modes and intermittent turbulence in various stages of development. This study examines the horizontal structure of a very stable atmospheric boundary layer, using data obtained primarily from terrain-following aircraft flights over central Oklahoma. Several diagnostic procedures are applied to the aircraft data, including classical and rotary spectral analysis, principal component analysis, and structure functions. Coherent structures with sharp boundaries are examined with a new conditional sampling technique which requires little a priori specification of sampling criteria. Because the flows involve sharp boundaries, spectral techniques do not provide as much useful information as other more localized procedures. The edges of the coherent structures are regions of significant vertical heat transport, a feature not often emphasized in studies of gravity waves and vortical modes in the stable boundary layer. The presence of significant turbulence even for large stability has implications for modelling of the very stable boundary layer. Forecasts of minimum temperature, boundary layer height, inversion characteristics, and pollutant dispersal are all significantly affected by turbulent mixing. Many models of the stable boundary layer artificially arrest the mixing under stable conditions, resulting in, for example, overestimates of nocturnal cooling. A new parameterization of the stable boundary layer is studied here by incorporating it into an existing model of the planetary boundary layer. The model is then run with one-dimensional sensitivity tests for an idealized atmosphere and with data from Wangara day 33. A simulation over snow cover is also examined. The tests substantiate the role of vertical mixing in ameliorating nocturnal cooling. An additional improvement is a more realistic boundary layer height for moderate wind speeds. / Graduation date: 1988

An analytical two-layer model consisting of a time-dependent stratified boundary layer topped by stratified free flow is developed in order to study atmospheric boundary layer production of vertical motion. To avoid use of a constant eddy viscosity, the boundary layer equations are layer-integrated over a fixed depth, and surface stress is parameterized using a linearized drag law. For flows driven by periodic, differential surface heating, it is found that the influence of accelerations, stratification, and friction are to concentrate the maximum convergence near a preferred latitude. The preferred horizontal length scale for boundary layer production of vertical motion increases with boundary layer stratification and decreases with distance from the preferred latitude. / Graduation date: 1980

The influence of boundary layer pumping on an externally-forced synoptic-scale flow is examined. The results follow earlier theories of stratified incompressible Boussinesq flow. These theories state that the spin-down time scale and the penetration depth of the influence of boundary layer pumping are inversely proportional to the stratification and directly proportional to the horizontal length scale of the flow. However, the present development is performed in isentropic coordinates which allow estimates applicable to the atmosphere, and implicitly includes nonlinear influences due to tilting and vertical advection. This analysis indicates that boundary layer pumping could be important synoptically in the lower troposphere under conditions of significant surface stress and tropospheric stratification. The influence of stratification and accelerations on synoptic-scale, boundary layer production of vertical motion is examined for the case of oscillating boundary-layer flow driven by time-dependent, horizontally- periodic surface temperature perturbations. It is found that only very strong stratification can significantly reduce the boundary layer pumping through pressure adjustments within the boundary layer. As a step in understanding the complicated dynamics of the structure of accelerated stratified boundary layers, order-of-magnitude analyses of variables for each layer are examined. This structure depends on the relative magnitude of the non-dimensional forcing frequency and the product of the stratification parameter and Ekman number. Applications to both synoptic and diurnal atmospheric circulations are considered. / Graduation date: 1978