The applicability of computational fluid dynamics (CFD) modelling schemes to turbulent wall-bounded flows is a matter of concern. In the near-wall region of bounded flows, the standard high Reynolds number k-e model is not valid and requires the use of empirical wall models to mimic the behaviour of this region. A theoretical study of the physics of prevalent wall modelling techniques showed that the velocity distribution took no account of the pressure gradient. To determine the effect of this shortcoming, a typical transient three-dimensional flow was analysed using current CFD methods and the results compared with experimental flow measurements. Consideration of these results showed that the 'traditional' wall model was unable to replicate observed flow features in the near-wall region: further analysis of the computational results confirmed that these poor flow predictions arose from the inability of the model to consider local pressure gradient effects. Consequently, a strong case was made for a more robust wall model for use in conjunction with the standard high Reynolds number k-e model. A number of boundary layer analyses were reviewed and Coles' law of the wake (1956) presented as a viable candidate for the development of a new wall modelling scheme. In theory, Coles' law (1956) provides a description of bounded flows under arbitrary pressure gradients up to the point of near-separation and may be extended to the study of reversed flows. A generic algorithm for Coles' law was prepared and used to study the fundamental test cases of U-bend and backward facing step flows. In a comparison between documented experimentation, 'conventional' CFD modelling and Coles' law models of these flows, the Coles' law model was shown to provide a viable alternative to 'traditional' schemes. Consequently, the Coles' law model of the near-wall region, being valid for pressure-driven flows, offers an extension to the range of flows for which the standard high Reynolds number k-e model may be used.

Bibliography: leaves 173-183. / xviii, 183 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Demonstrates that the local strain rate in the fluidic precessing jet (FPJ) flames is reduced by an order of magnitude relative to momentum dominated simple jet flames and this difference is shown to correlate with reduced NOx emissions and increased emissivity. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 1998

Thesis (M.S.)--University of Michigan, 1977.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xxiii, 187 p.; also includes graphics Includes bibliographical references (p. 179-187). Available online via OhioLINK's ETD Center

Thesis (M.S.)--University of Michigan, 1977.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Ari Glezer; Committee Member: Marc Smith; Committee Member: Yogendra Joshi.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

No description available.

The use and supply of various organic solvents for analytical chemistry is coming under scrutiny due to their environmental impact. International legislation now prevents the supply of "ozone depleting" solvents for laboratory purposes. Consequently alternative analytical methods to those which had previously relied upon the use of a range of organic solvents need to be developed. Supercritical fluids exhibit some properties associated with gases and liquids, and in particular their solvating characteristics are equivalent to a wide range of conventional organic solvents. Environmentally benign carbon dioxide in its supercritical fluid state can be utilised to imitate the solvating power of a range of organic solvents from non polar pentane through to more polar pyridine. There are many reports detailing the use of supercritical fluid extraction for the isolation of target compounds from a very wide range of solid matrices. The objective of these studies was to develop direct liquid supercritical fluid extraction procedures using carbon dioxide to isolate, concentrate and quantify target analytes from aqueous media. These investigations involved using off-line and on-line supercritical fluid extraction procedures with final analytical detection and quantification being accomplished using a range of chromatographic, spectroscopic and mass spectrometric methods. Within chapters 2 and 3, an alternative infrared method for determining the quantity of oil in process and discharge waters is described. The results of quantification studies involving various oils and hydrocarbons indicate that the custom built supercritical fluid extraction system developed for these investigations directly coupled with an infrared spectrometer provide an alternative method to traditional liquid-liquid extraction procedures that involve the use of ozone depleting and/or toxic organic solvents. Chapter 4 describes how direct aqueous supercritical fluid extraction was used to continuously isolate free testosterone as it was liberated during the enzymic digest of a testosterone-/3-D-glucuronide solution incubated with Helix pomatia glucuronidase. Other studies described within this chapter that also involved the use of direct aqueous supercritical fluid extraction with off-line gas chromatography-mass spectrometry describe procedures for determining trace levels of organophosphate pesticides and polyaromatic hydrocarbons in aqueous samples. The development and use of on-line direct aqueous supercritical fluid extraction coupled with supercritical fluid chromatography-mass spectrometry using atmospheric pressure chemical ionisation for the analysis of phenols at the ppb level is described in Chapter 5. Chapter 6 describes the use of direct aqueous supercritical fluid extraction coupled online with liquid chromatography-mass spectrometry using ammonia chemical ionization for the analysis of three veterinary drugs at the ppb level. Results of off-line and on-line studies involving electrospray tandem mass spectrometry with high pressure liquid chromatography for the analysis of a range of ionophores at the low ppb level following their isolation using direct aqueous supercritical fluid extraction are also presented.

D.Ing. / The aim of this thesis is to research the use of Computational Fluid Dynamics (CFD) as design tool to predict fluid flow across stationary and moving bluff bodies. The principle of moving meshes is introduced to move the body vertically with respect to time. The moving mesh idea is first tested on a square body with a coarse discretized flow domain for transient conditions. The results can be animated to see how the flow pattern and mesh change with time. The idea is then implemented on a cylinder with a very fine mesh to capture the build-up and dispersion of vortices being shed from the cylinder as it moves cyclically for transient conditions. With this first approach a bluff body is forced to move cyclically with respect to time in cross flow. Many possibilities now exist to apply this idea further for other applications where forced vibration is important.The next approach is to use CFD to simulate flow-induced vibrations of bluff bodies. The pressure force on the bluff body is considered as a first approach to solve this problem. The inertia mass of the body balancing the effect of the pressure force on the body is first used, but the results indicate that damping and stiffness also have to be considered to obtain more realistic results. The effect of the pressure force on the body shows generally a downwards movement of the body for the first period of simulation and in the case of the square, after six time steps of the period of simulation the .pressure force switches to a positive value with resulting upwards movement of the body. The effect of the total force (shear + pressure) on a bluff body is not presented in this thesis. CFD as design tool is researched for various bundle configurations of cylinders. A new concept of split cylinders is researched and the best configuration obtained for various horizontal and vertical spacings of downstream- and upstream cylinders and cylinder halves. Experimental results on cylinders in a - small scale wind tunnel are used to compare the numerical results with the obtained pressure distribution around a stationary cylinder and the concept of velocity distribution over and between a split cylinder. Further development of the numerical flow model is necessary to include elasticity and longer three dimensional spanwise lengths of the object to obtain predictions of real flow-induced vibrations of bluff bodies. This first approach of numerical predictions of flow across stationary and moving bluff bodies creates many possibilities of complementing experimental results and comparing the obtained results with each other.