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Whitianga Estuary is a bayhead barrier type estuary located on the east of the Coromandel Peninsula, North Island, New Zealand. The catchment has undergone many land-use changes since pre-European settlement. In some areas of the catchment land-use has changed from native forest to grasslands to forestry and back to pasture. These changes in catchment land-use all contribute to increased sedimentation into the estuary. Development of the estuary itself has also occurred in recent times. Much growth has been focussed around the estuary due to Whitianga town-ship having a large boating community, and includes a 170 berth marina and wharf situated at the tidal inlet entrance to the estuary. These, and the extensive canal development engineering works can have substantial impacts on the sedimentation regime, and may modify tidal circulation, flushing, and sediment deposition within the estuary. The principle aim of this research is to assess hydrodynamics and sedimentation of the estuary for future management and development purposes, and also to model different scenarios in order to determine the most cost effective, and least obtrusive design for a proposed boat-ramp and approach channel near the marina. To determine sedimentation rates, sediment cores from four locations were collected to depths of 1 m. Coring locations were chosen based on preliminary model run results, selecting areas that appeared to be long-term sediment sinks of a stable nature. Cores were divided into 10 mm sections and prepared for 210Pb dating and heavy metal analysis, to make an assessment of the vertical sedimentation rates. Recent sedimentation rates were found to be as high as 9 mm/yr post-1950s and past sedimentation rates as high as 30 mm/yr pre-1950s. The use of heavy metal analysis for dating proved difficult as the background levels of the conservative elements used to normalise results varied, making the geochemical analysis approach inappropriate. As bathymetry is one of the most important aspects of modelling, a large amount of surveying was undertaken for this study. LiDAR, singlebeam data, and recent rectified aerial photographs were interpreted for the creation of a bathymetric grid file to be used for hydrodynamic modelling of the estuary. The 3DD numerical model was used to determine tidal flows and current velocities. From this initial hydrodynamic model a particle-tracking model was created to determine sediment transport pathways within the estuary. From the initial 20 m model it was then possible to create a number of nested model grids for the purpose of determining the best practice scenario for the creation of a proposed boat ramp and associated approach channel near the harbour entrance. Hydrodynamic results suggest that residual circulation in Whitianga Estuary is nearly in balance, with a low ebb tidal domination present. Particle tracking results suggest that sediment entrained and carried into and within the estuary will accumulate on the intertidal flats. Sediment transport modelling indicates that the impact of a proposed boat-ramp will result in sedimentation of the dredged approach channel due to reductions in residual and tidal velocities.

In the design of all marine craft the prediction of a vessel??s resistance characteristics is a major consideration. The accurate prediction of resistance is particularly important in the design of modern high-speed vessels where the primary contractual obligation placed upon the builder is the vessel??s achievable speed. Investigation was made of the methods of Doctors and Day, whereby the traditional Michell wave-resistance theory, published in 1898, is improved on through a better understanding of the hydrodynamics of transom sterns and the application of statistically determined form factors. One of the difficulties with the Michell theory is how to account for the hollow that forms behind a transom stern, a feature prevalent in high-speed vessels. A common approach in the numerical prediction of wave resistance for transom-stern vessels is to discretize the hollow as a geometrically-smooth addition to the vessel. Therefore, of great importance in accurate prediction of wave resistance is the hydrodynamics of, and in particular, the length and depth of the hollow formed behind the transom stern. Accordingly, a systematic series of transom-stern models were tank tested at various drafts and speeds in order to determine experimentally the length and depth of the hollow as a function of vessel speed, draft and beam. From the experimental data, algorithms for the determination of the length and depth of the transom hollow, have been developed and utilised in the discretization of the transom hollow for prediction of resistance using the Michell wave- resistance theory. Application of the developed hollow algorithms produced significant improvements in correlation of the experimental and theoretical predictions of total resistance, particularly in the lower Froude range. In addition to the transom-hollow investigation, form factors were obtained using least-squares regression of existing experimental data. The form factors were based on the major geometric parameters of the models used. In the research presented here, the method was applied to a large range of published resistance data for high-speed displacement vessels. Considerable improvement in correlation, between theoretical and experimental predictions of total resistance, was obtained by incorporating the calculated form-factors into the total resistance formulation.

The molecular weight distributions of two high molecular weight (M[subscript w]>>1 million) polyethylene polymers, WSR-308 and WSR-301, were characterized with gel permeation chromatography (GPC) coupled with a multi-angle laser light scattering detector (MALLS). The M[subscript w] of the WSR-308 was found to be 5.10x10⁶ g/mol with a molecular weight range from about 1 million g/mol to as high as 10 million g/mol. The M[subscript w] of the WSR-301 was found to be 3.16x10⁶ g/mol with the lowest molecular weight about 400,000 g/mol while the highest molecular weight component may have been as high as 8 million g/mol. Attempts to measure the M[subscript w] of the two polymers using static light scattering (SLS) techniques proved to be difficult. In conjunction with these studies, drag reduction and shear degradation studies of the two polymers in water were also conducted. Solutions of the two polymers, ranging from 1 to 10 ppm including mixtures of the two, were tested in a pipe-flow apparatus to obtain friction factor and %DR data. In every case, the greater the concentration and/or the molecular weight of the polymer, the greater the drag reduction effects. Additionally, the higher molecular weight polymer and mixtures with a greater weight percentage of the higher molecular weight polymer were found to shear degrade less quickly than otherwise. A unique point along the maximum drag reduction asymptote (MDA) termed the "divergence point" was a focus of this study and an energy model based on frictional losses correlates well to the data. The correlation developed here relates the difference in frictional losses between the solvent by itself and the polymer solution directly to the mass concentration and molecular weight of the polymer. This frictional difference was proportional to the product of the mass concentration and molecular weight where both quantities were to approximately the first power. / Graduation date: 2002

The hydrodynamics of an agitated tank have been studied byphase-Doppler anemometry. The focus is on the impeller anddischarge region of a 45o pitched blade turbine (PBT). Thestudy includes agitation of pure water as well as of a dilutesuspension of process particles. A three-dimensionalphase-Doppler anemometer is used to measure local,instantaneous, three-dimensional velocities of the fluid and ofthe suspended particles. A shaft encoding technique is used toresolve the turbulent fluctuations from the periodic velocityfluctuation due to the impeller blades, and to provide moredetailed information about the variations relative to theimpeller blade. Velocity bias is corrected for by the total3-dimensional velocity. The mean flow field, the fluctuating velocities, and thecomplete Reynolds stress tensor, are reported for the liquidphase flow. The periodic fluctuations in the flow that aregenerated by the impeller blades are eliminated in theexamination of the turbulence. The anisotropy of the turbulenceis assessed by the invariants of the anisotropy tensor. Thetrailing vortex structure is demonstrated to be associated withhigh kinetic energy and strong anisotropy of the turbulence.The vortex is still observable 130-140 degrees behind theblade. It gradually moves down from the impeller blade but thelocation in radial direction remains essentially unchanged. Theinfluence of the periodic fluctuations is examined and it isshown that the turbulence appears more isotropic when theperiodic fluctuations are not eliminated. The solid particle concentration is low below the impellerand is high above the impeller tip. The particles diverge fromthe liquid flow mean direction, especially below the agitatorclose to the tip where the strongest turbulence is found.Periodic fluctuations in the particle concentration relate tothe variations found in the angle-resolved mean velocity andfluctuating velocity. The ratio of the maximum to the minimumconcentration is about 2.0 in the present study. The baffles influence on the conditions in the impellerregion, and this influence can be observed on the fluid meanvelocity field, the angle-resolved velocities, the kineticenergy, and on the behavior of larger process particles. In theimpeller region the highest kinetic energies are about 15%higher upstream of the baffle than at the middle plane betweenthe baffles. The highest energy level in the middle plane isactually the lowest value and is therefore not representativewhen rotation symmetry is assumed. Local energy dissipation rates have been investigated, andthe integration of the local energy dissipation rates overdifferent control volumes has been compared with macroscopicenergy balance calculations. The discrepancy is significant.Different reasons have been analyzed and recommendations forfurther investigation are given. I n the outflow region there is a significant variation alsoin the direction of the instantaneous velocity, which may leadto direction bias in the case of non-spherical measurementvolume. In order to account for this direction bias, amathematical model is developed to estimate the projected areaof the measurement volume in LDA or PDA. It is shown that theprojected area variation can lead to a significant directionbias in determination of time averaged values and localparticle concentration in a highly turbulent stirred tank flow.This bias is however negligible for an orthogonal optical setup, as is used in the present study. <b>Keywords:</b>Hydrodynamics, phase-Doppler anemometer,suspension, pitched-blade turbine, anisotropy, turbulence,Reynolds stresses, trailing vortex, kinetic energy, stirredtank

Controlled cooling is an important part of steel production industry that affects the properties of the outcome steel. Many of the researches done in controlled cooling are experimental. Due to progress in the numerical techniques and high cost of experimental works in this field the numerical work seems more feasible. Heat transfer analysis is the necessary element of successful controlled cooling and ultimately achievement of novel properties in steel. Heat transfer on the surface of the plate normally contains different regimes such as film boiling, nucleate boiling, transition boiling and radiation heat transfer. This makes the analysis more complicated. In order to perform the heat transfer analysis often empirical correlations are being used. In these correlations the velocity and pressure within the fluid domain is involved. Therefore in order to obtain a better understanding of heat transfer process, study of hydrodynamics of the fluid becomes necessary. Circular jet due to its high efficiency has been used vastly in the industry. Although some experimental studies of round jet arrays have been done, yet the characteristics of a single jet with industrial geometric and flow parameters on the surface of a flat plate is not fully understood. Study of hydrodynamics of the jet impingement is the first step to achieve better understanding of heat transfer process. Finite element method as a popular numerical method has been used vastly to simulate different domains. Traditional approaches of finite element method, Lagrangian and Eulerian, each has its own benefits and drawbacks. Lagrangian approach has been used widely in solid domains and Eulerian approach has been widely used in fluid fields. Jet impingement problem, due to its unknown free surface and the change in the boundary, falls in the category of special problems and none of the traditional approaches is suitable for this application. The Arbitrary Lagrangian Eulerian (ALE) formulation has emerged as a technique that can alleviate many of the shortcomings of the traditional Lagrangian and Eulerian formulations in handling these types of problems. Using the ALE formulation the computational grid need not adhere to the material (Lagrangian) nor be fixed in space (Eulerian) but can be moved arbitrarily. Two distinct techniques are being used to implement the ALE formulation, namely the operator split approach and the fully coupled approach. This thesis presents a fully coupled ALE formulation for the simulation of flow field. ALE form of Navier-Stokes equations are derived from the basic principles of continuum mechanics and conservation laws in the fluid. These formulations are then converted in to ALE finite element equations for the fluid flow. The axi-symmetric form of these equations are then derived in order to be used for jet impingement application. In the ALE Formulation as the mesh or the computational grid can move independent of the material and space, an additional set of unknowns representing mesh movement appears in the equations. Prescribing a mesh motion scheme in order to define these unknowns is problem-dependent and has not been yet generalized for all applications. After investigating different methods, the Winslow method is chosen for jet impingement application. This method is based on adding a specific set of partial differential Equations(Laplace equations) to the existing equations in order to obtain enough equations for the unknowns. Then these set of PDEs are converted to finite element equations and derived in axi-symmetric form to be used in jet impingement application. These equations together with the field equations are then applied to jet impingement problem. Due to the number of equations and nonlinearity of the field equations the solution of the problem faces some challenges in terms of convergence characteristics and modeling strategies. Some suggestions are made to deal with these challenges and convergence problems. Finally the numerical treatment and results of analyzing hydrodynamics of the Jet Impingement is presented. The work in this thesis is confined to the numerical simulation of the jet impingement and the specifications of an industrial test setup only have been used in order to obtain the parameters of the numerical model.

This thesis examines transport phenomena of cupric chloride (CuCI2) hydrolysis within a fluidized bed. Conversions of CuCi2 and steam as a fluidizing gas are numerically investigated using a new non-catalytic gas-solid reaction model, proposed in the literature but here updated for the purposes of the present study. The results are illustrated considering two cases of kinetics for the consumption of particles: Volumetric Model and Shrinking Core Model. Consistent results in terms of the conversion of reactants versus superficial velocity, bed inventory and bed temperature are obtained by developing new solution algorithms abased on each of the above kinetic models. / UOIT

Hydrodynamic effects play important roles in fluidized bed combustion processes. Since the motion of "bubbles" is an important influence on fluidized bed heat transfer, a better understanding of their behavior is necessary for improving the design of fluidized bed boilers. Using a two-dimensional bed, silica sand particles were fluidized with air at room conditions. The bubbling bed was videotaped, and both qualitative and quantitative information were gathered. Bubble characteristics such as size, rise velocity and frequency were studied while particle size and superficial gas velocity were varied. Results were compared with some existing theories and other similar research. The effect of internal surfaces at several heights in the bed was also studied. General bubble behavior agreed well with descriptions from previous research, and the expected spherical-cap bubble shape was observed. Both bubble size and rise velocity increased with particle size and with fluid velocity. Bubble frequency increased with fluid velocity, but decreased with increasing particle size and height in the bed. These results agree with previous work done using optical probes to measure bubble characteristics. Comparisons of data with empirical models showed general agreement. The presence of internal surfaces had the effect of reducing the bubble size, rise velocity, and frequency, and also of reducing the influence of changing particle size and superficial velocity on the bed behavior. / Graduation date: 1992

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