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Characteristics of the flow field and of impingement surface heat transfer for round, turbulent jets were studied experimentally. / The effects on the flow field and heat transfer of nozzle geometry, i.e. nozzle length, l(,n)/d(,n), and nozzle entrance configuration (contoured and sharp-edged), and semi-confinement were investigated. In addition, the role of suction on the development of flow was considered. / Effects of nozzle geometry on the flow field and on heat transfer are to divide the nozzles tested into two groups; the long (10 (LESSTHEQ) l(,n)/d(,n) (LESSTHEQ) 50) nozzles with similar characteristics and modest differences between them, and the short (l(,n)/d(,n) = 1) nozzles with distinctly different patterns for flow and heat transfer. / Semi-confinement restricts interaction and mixing between the jet and the ambient fluid and hence reduces entrainment, and causes significant reductions in local heat transfer coefficients over most of the impingement surface. / In general, application of suction up to V(,w) = 0.25 m/s or 0.42% of the nozzle exit average velocity reduces the boundary layer thickness, increases radial velocities adjacent to the impingement surface, thereby velocity gradients near the wall.

In the study of computational turbulence, the success of Large Eddy Simulation (LES) is largely determined by the quality of the sub-filter scale (SFS) model and the properties of the filter used to introduce resolved and unresolved length scales. Explicit filters are desirable so that better control over the filter may be achieved, and filter operator errors can be then controlled to a desired order of accuracy. One large advantage to using an explicit filter is that the mathematical definition of the filter may be exploited when considering various SFS models or even different LES techniques. Approximate deconvolution is a technique used in LES, which performs an inverse filtering operation to partly restore the original unfiltered solution. The discrete explicit filtering technique will be used to perform the deconvolution, and numerical results will show how the approximate solution may be used to perform LES.

In the study of computational turbulence, the success of Large Eddy Simulation (LES) is largely determined by the quality of the sub-filter scale (SFS) model and the properties of the filter used to introduce resolved and unresolved length scales. Explicit filters are desirable so that better control over the filter may be achieved, and filter operator errors can be then controlled to a desired order of accuracy. One large advantage to using an explicit filter is that the mathematical definition of the filter may be exploited when considering various SFS models or even different LES techniques. Approximate deconvolution is a technique used in LES, which performs an inverse filtering operation to partly restore the original unfiltered solution. The discrete explicit filtering technique will be used to perform the deconvolution, and numerical results will show how the approximate solution may be used to perform LES.

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No description available.

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Computational Fluid Dynamics (CFD) are used to investigate two speech phenomena. The first phenomenon is the English bilabial plosive /pa/. Simulations are compared with microphone recordings and high speed video recordings to study the penetration rate and strength of the jet associated with the plosive /pa/. It is found that the dynamics in the first 10ms of the plosive are critical to penetration rate, and the static simulation was not able to capture this effect. However, the simulation is able to replicate the penetration rate after the initial 10ms. The second speech phenomenon is the English fricative /sh/. Here, the goal is to simulate the sound created during /sh/ to understand the flow mechanisms involved with the creation of this sound and to investigate the simulation design required to predict the sound adequately. A variety of simulation methods are tested, and the results are compared with previously published experimental results. It is found that all Reynolds-Averaged Navier-Stokes (RANS) simulations give bad results, and 2D Large Eddy Simulations (LES) also have poor results. The 3D LES simulations show the most promise, but still do not produce a closely matching spectra. It is found that the acoustic analogy matches the direct measurements fairly well in 3D simulations. The studies of /pa/ and /sh/ are compared and contrasted with each other. From the findings of the studies, and using theoretical considerations, arguments are made concerning which CFD methods are appropriate for speech research. The two studies are also considered for their direct applications to the field and future research directions which might be followed.

Thesis (PhD)--University of South Australia, 1999

Typescript (photocopy) / xviii, 396 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.)--Dept. of Mechanical Engineering, University of Adelaide, 1980