To understand how the input impedance of the respiratory system relates to pressure and volume airflow of the airway branched structure, this thesis focuses on developing a mathematical model of the branched airway including trachea and branching airways. The 5-Lobe lung model is developed mathematically and experimentally. A computer model is constructed in the MathlabTM programming environment. It accounts for the effects of airways with varying cross-sectional area, flexible wall properties, and the bronchial tree within the lung using the mathematical methods developed in previous researches. The terminal impedances are determined by proposed idealized lobe models. A range of frequencies up to 256 Hz are tested on this model. Cases of study on obstructions by varying lung stiffness from healthy to unhealthy conditions are investigated.Mathematical model is validated by experiment investigations on the mechanical lung simulator, which is built in Diagnostic & Control Research Centre at Auckland University of Technology. The results conclude that mathematical methods used in this research are capable to produce predictable results of the input impedance.

Typescript. Bibliography: leaves 145-150.

Errata sheet inserted. Bibliography: leaves 99-102.

viii, 102 leaves : ill., 3 pams in back pocket / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.) from the Dept. of Mathematics, University of Adelaide, 1968

vi, 164 leaves : ill., tables, maps, photos ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1978) from the Dept. of Applied Mathematics, University of Adelaide

"November 2001" / Includes bibliographical references (leaves 235-240) / xiii, 285 leaves : ill. (some col.) ; 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 Civil and Environmental Engineering, 2003

Graduation date: 1975

A modeling study is undertaken to better understand the physics of katabatic flows. This study is divided into three topics; a comparison between a large eddy simulation (LES) and a mesoscale model of katabatic flows, a sensitivity study of katabatic flows to various physical parameters, and an investigation into the effect of subgrid scale terrain features on katabatic flow models. In the first topic, a comparison between LES, and a mesoscale model, ARPS, of katabatic flows is made to better quantify the accuracy of subgrid parametenzation in ARPS. It is shown that, although the modeled flows agree on a number of parameters, the LES model produces a lower and faster jet than that of ARPS, and also cools more near the surface. The momentum budgets of the two models agree well with each other. The ARPS model has a higher amount of TKE than the LES model, due to an overproduction by shear in the ARPS subgrid parameterizations. The second portion of this thesis represents a sensitivity study of katabatic flows to various physical parameters. The depth and strength of katabatic flows are shown to vary with surface heat fluxes, slope angle, and ambient stratification. Katabatic flows are shown to grow in depth and magnitude as slope angle increases, due to an increase in entrainment of overlying ambient air. The ratio of advection to mixing is shown to collapse to a near universal value regardless of surface heat fluxes. With increasing ambient stratification, entrainment in katabatic flows becomes small and the momentum equation is reduced to a two-way balance between buoyancy and drag. In this case, the heat flux of entrained air into the katabatic flow approaches that of the surface cooling, and the flow ceases to grow in the down-slope direction. Finally, predictions for bulk velocity and buoyancy strength scales are developed as a function of slope angle and surface heat fluxes. The last portion of this study focuses on the effect of subgrid scale terrain features on katabatic flows. It is shown that in areas of inadequate terrain resolution, the effect of the terrain smoothing routine in ARPS is to increase the slope height in areas of concave mountains. The concept of energy conversion in katabatic flows is introduced, and it is shown that the effect of raising terrain is to assign parcels more buoyant potential energy than they would otherwise have, and thus over-predict the magnitude of katabatic flows. Finally, an investigation into the effect of changing upper slope angle on katabatic flows over combined slopes is made. It is concluded that a combined slope cannot be predicted using a linear combination of simple slopes, since the transition portion of the slope results in a turbulent hydraulic jump with enhanced mixing. The magnitude of mixing in the turbulent hydraulic jump in combined slopes is shown to depend on the difference between upper and lower slope angle. / Graduation date: 2004

A global, multi-level, wave-mean flow model based on an approximate version of the primitive equations is developed to investigate the development of a baroclinic wave field initially confined to a single zonal wavenumber. The effects of physical processes (surface drag and thermal damping) and internal diffusion on the evolution have been examined. The nature of the mean flow adjustment by the nonlinear baroclinic waves is also studied. For a simulation with a relatively strong internal diffusion it is found that a single life cycle characterized by baroclinic growth and barotropic decay is obtained (as in Simmons and Hoskins, 1978), whereas with weaker diffusion the wave undergoes secondary life cycles before a nearly wave-free state is reached (as in Barnes and Young, 1991). In an experiment with weak 4th order diffusion secondary life cycles occur with little net decay. Relatively strong barotropic growth follows the initial life cycle. In experiments with surface drag (Rayleigh friction) and thermal damping (Newtonian cooling), repeated life cycles of baroclinic growth and barotropic decay can be obtained. It is found that in the complete absence of surface drag, the flow evolves to a nearly wave-free state after one secondary cycle. This demonstrates that surface drag plays an important role in nonlinear baroclinic instability. With relatively strong surface drag multiple life cycle behavior is found for sufficiently strong thermal damping. Such a behavior strengthens for very strong thermal damping. A steady wave state in which the wave amplitude equilibrates at an essentially constant level has only been obtained with very strong "potential vorticity damping". Both the "barotropic governor" process (James and Gray, 1986) and the baroclinic adjusment process are responsible for major parts of the stabilization of the mean flow in simulations with and without surface drag and thermal damping. However, the "barotropic governor" process dominates the flow evolution in the model simulations without surface drag and thermal damping. The "barotropic governor" modifies the meridional gradient of zonal mean potential vorticity, which influences the baroclinic adjustment. / Graduation date: 1992

The thesis examines the applicability of a two-dimensional flow acceleration model to describe a terrain-induced flow perturbation as measured at Yaquina Head on the central Oregon coast. The geometry of Yaquina Head together with the upstream wind values were used in estimating hilltop winds. These estimates compare well with the observed wind values. A second method to estimate the hilltop winds was attempted by developing a mean ratio of Yaquina Head winds to the upstream Yaquina South Jetty winds. This ratio was taken from one winter's data and used to estimate the next winter hilltop winds. The same upstream wind values were used with this method as were used with the geometric model. Statistical evaluation in the form of regression analysis was performed to determine the ability of the geometric and statistical models to estimate the hilltop wind on Yaquina Head. It was found that both models did reasonably well but that neither model was appreciably better than the other. / Graduation date: 1979