The purpose of this study was to investigate the velocity distribution through an annular bed packed randomly with equal sized spheres. Extensive research has been conducted on the velocity distribution inside packed beds packed with equal sized spheres, different sized spheres, deformed spheres, cylinders and Raschig-rings. A majority of these experimental and numerical studies focused on the cylindrical packed bed. These studies and numerical models are all confined to the velocity profile once the fluid flow is fully developed. The development of the velocity through the inlet region of the bed and the fluid flow redistribution in the outlet of the bed is thus neglected. The experimental investigation into the velocity distribution down stream of the annular packed bed of the HTTU indicated that the velocity profile was independent of the mass flow rate for a particle Reynolds number range of 439 £ Re £ 3453 . These velocity profiles did not represent the distribution of the axial velocity due to shortcomings associated with the single sensor hot wire anemometry system used to measure the velocity distribution. A numerical investigation, using the RANS CFD code STAR-CCM+®, into the velocity distribution downstream of an explicitly modelled bed of spheres indicated that the axial velocity distribution could be extracted from the experimental velocity profiles by using an adjustment factor of 0.801. This adjusted velocity profile was used in the verification of the implicit bed simulation model. The implicit bed simulation model was developed in STAR-CCM+®. The resistance of the spheres was modelled using the KTA (1981) pressure drop correlation and the structure of the bed was modelled using the porosity correlation proposed by Martin (1978), while the effective viscosity model of Giese et al. (1998), adjusted by a factor of 0.8, was used to model the velocity distribution in the near wall region. It was found that the structure in the inlet region of the bed, where two walls disturb the packing structure, can be modelled as the weighted average of the radial and axial porosity while the structure in the outlet regions can be modelled by letting the radial porosity increase linearly to unity. The basic shape of the velocity profile is established immediately when the fluid enters the bed. The amplitude of the velocity peaks however increase in magnitude until the velocity profile is fully developed at a distance approximately of five sphere diameters from the bed inlet. The profile remains constant throughout the bed until the outlet region of the bed is reached. In the outlet region a significant amount of fluid redistribution is observed. The amplitude of the velocity peaks is reduced and the position of the velocity peaks is shifted inwards towards the centre of the annular region. The fully developed velocity profile, predicted by the simulation model is in good agreement with profiles presented by amongst others Giese et al. (1998). The current model however also offers insight into the development of the profile through the inlet of the bed and the fluid redistribution, which occurs in the outlet region of the bed. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.

Transporting cattle from southern Alberta into the United States (US) plays a substantial economic role in the western Canadian beef industry. Thermal environments within cattle transport trailers are dependent on ambient conditions, and if inadequately managed, can be a welfare concern. To effectively manage cattle transport, the environmental conditions throughout the livestock trailer must be understood. The objective of the present study was to investigate the trailer micro-climate and welfare during 5-paired commercial long-haul transports of slaughter cattle from Alberta, Canada to Washington State, US during summer months. In addition, the effect of compartment location and trailer porosity (8.7% vs 9.6%) on trailer micro-climate, shrink and core body temperature were also investigated during the warmest in-transit hour and stationary events. The compartment location had an effect on micro-climate variables where the upper compartment had greater (P < 0.05) temperature than the bottom deck compartments and relative humidity variables had the opposite effect for both the warmest in-transit hour and stationary events. There was also an effect of trailer porosity on micro-climate variables where it was generally warmer in the trailer with the higher porosity in the stationary event. Differences between trailers included 2 additional roof hatches on the trailer with lower side-wall porosity and lower internal temperatures, which could suggest the location of the trailer porosity, could be important for heat and moisture exchange during transit. The nose of the trailer with higher porosity had generally warmer internal conditions (larger T(trailer)°C and THI(trailer)) than the trailer with lower porosity. This study also found that the temperatures inside the trailer can be 10.5°C greater than ambient temperatures during stationary events and 9°C greater than ambient levels during the warmest in-transit hour. The average amount of per-animal weight loss was 4.3 0.3 % and was affected by trailer porosity and compartment, which followed the trends in thermal environment variables. The transit status (stationary or in-transit) and trailer porosity affected the vaginal core body temperature of the heifers in transit. The core body temperature was greater during stationary events for animals transported in the trailer with lower porosity. It is suggested that the lower side-wall porosity and/or the shape of perforation pattern could impair the movement of fresh air to the respiratory tract of heifers, thus impacting the main mechanism for dissipating heat. The difference in temperature from the trailer ceiling to the animal level was 3.38°C in the trailer with lower porosity (cooler at the ceiling) and 2.23°C in the trailer with the higher porosity. This relationship also had a compartment location effect that followed the micro-climate compartmental differences. This could suggest that excess heat in the trailer with the lower porosity, that also had lower overall temperatures, exited through roof hatches, while in the trailer with the higher porosity, the heat escaped through the side-wall perforations. This theory also supports the idea that the location of where the porosity is located on the trailer may be important to alleviating heat stress in summer months during transport. The results of this study also indicated that there was no difference in the location of the data logger plane (driver, middle passenger) and within the compartments (front, middle, back), suggesting that compartment location effect is substantial when considering micro-climate but temperatures within a compartment are mostly homogenous. The trip that had average ambient temperatures of 25.9 ± 6.06°C for the entire journey, had a temperature Humidity Index that was considered in the danger or emergency category according to the Livestock Weather Heat Index during 95% of the warmest in-transit hour. This suggests that during ambient temperatures of 25.9°C, both trailers used in this study did not have sufficient heat exchange to mitigate the risk of heat stress for cattle.

The main goal of the present study is to investigate the energy dissipation through inclined screens. Recent studies have shown that screens arranged vertically may dissipate more energy than a hydraulic jump does below small hydraulic structures. In the present study a series of laboratory experiments were performed in order to determine the effect of inclination of the screen on the energy dissipated by the screen. The porosity of the screen used in the experiments is 40%. Inclination angle, thickness of the screen, location of the screen, upstream flow depth, and the Froude number of the upstream flow are the major parameters for the laboratory experiments. Froude number of the upstream flow covered a range of 5 to 24. A screen was located up to a distance 100 times the undisturbed upstream flow depth from the gate and the thickness of the screen was changed in correlation with the depth of upstream flow. The results of the experiments show that the inclination parameter has an insignificant effect on the energy dissipated by the screen. Namely, inclination of the screen does not contribute much in reducing the energy of the flowing water further, compared to vertically placed screens.

ABSTRACT EXPERIMENTAL INVESTIGATION OF ENERGY DISSIPATION THROUGH TRIANGULAR SCREENS G&uuml / ng&ouml / r, Endam M.Sc., Department of Civil Engineering Supervisor: Assoc. Prof. Dr. Zafer BozkuS Co-Supervisor: Prof. Dr. Metin Ger May 2005, 82 pages For the present study, a series of experimental works are executed to dissipate energy through triangular screens. Recent studies have shown that the implementation of the screen for energy dissipation is an effective way to extract out the excessive energy of water downstream of small hydraulic structures located in rivers of relatively negligible sediment content. In the present study, double screen arrangement with a porosity of 40% is used. The inclination angle of the screens is opted as 60 degree. The major parameters for the present study are upstream flow depth, location of the screen together with the supercritical upstream flow Froude number for a range covering from 7.5 to 25.5. The gate opening simulating a hydraulic structure is adjusted with various heights of 1 cm, 1.25 cm, 1.6 cm, 1.7 cm, 2 cm, 2.5 cm, 2.7 cm, 3.2 cm and 3.3 cm during the study. The results of the experiments show that the triangular screen configuration with the same pore geometry has no significant additional contribution on the energy dissipation as compared to vertically placed screens. Keywords: Screen, energy dissipation, triangular configuration, porosity, hydraulic jump, supercritical flow.

Wellbore seismic measurements were recorded in the Lake Bosumtwi impact structure, Ghana, in 2004. A full range of petrophysical measurements were also performed in the laboratory on core samples from the same boreholes. The Vertical Seismic Profile shows low velocities for both P and S waves in the hardrock basement of the crater. Although we were expected to locate fractures within the rock, no upgoing waves were detected. Density and porosity measurements on the core samples indicate higher than normal porosity in the impact damaged rocks. Mercury porosimetry and SEM analysis characterized the pores as impact induced microcracks. These microcracks are most likely the reason for the low velocities observed on the seismic profiles, the in situ sonic logs, and the seismic velocity measurements on the core samples. Furthermore our laboratory P and S velocities measurements indicate a strong heterogeneity within the impactites. / Geophysics

Solid oxide fuel cell (SOFC) research is currently underway to improve performance, cost and durability by lowering the operating temperature to ~600°C. One approach is to design fabrication processes capable of tailoring desirable cathode microstructures to enhance mass and charge transfer properties through the porous medium. The aim of this study is to develop a cost effective fabrication technique for deposition of novel microstructures, specifically, functionally graded thin films of LSM oxide with porosity graded structure for use as IT- SOFCs cathode. Spray pyrolysis method was chosen as a low-temperature processing technique for deposition of porous LSM films onto dense YSZ substrates. The effort was directed toward the optimization of the processing conditions for deposition of high quality LSM films with variety of morphologies in the range of dense to porous microstructures. Results of optimization studies on spray parameters revealed that the substrate surface temperature is the most critical parameter influencing the roughness and morphology, porosity, cracking and crystallinity of the film. Physical and chemical properties of deposited thin films such as porosity, morphology, phase crystallinity and compositional homogeneity have shown to be extensively dependent on the deposition temperature as well as solution flow rate and the type of precursor solution among other parameters. The LSM film prepared from organo-metallic precursor and organic solvent showed a homogeneous crack-free microstructure before and after heat treatment as opposed to aqueous solution. Also, increasing the deposition temperature and the solution flow rate, in the specific range of 520-580 ℃ and 0.73-1.58 ml/min, respectively, leads to change the microstructure from a dense to a highly porous film. Taking the advantage of simplicity of spray pyrolysis technique combined with using metal-organic compounds, the conventional ultrasonic spray system was modified to a novel system whereby highly crystalline multi-layered porosity graded LSM cathode with columnar morphology and good electrical conductivity in the range of 500-700 °C was fabricated through a multi-step spray and via applying optimum combination of spray parameters. This achievement for the current graded LSM cathode would allow its use in IT-SOFCs.

Biot's theory when applied to homogeneous media (involving the macroscopic flow mechanism) cannot explain the high level of attenuation observed in natural porous media over the seismic frequency range. However, several successful mesocopic inhomogeneity models have been developed to account for P wave attenuation. In this thesis I further develop the approaches to tackle S wave velocity and attenuation, to simulate transient wave propagation in poroelastic media, and to construct new models for determining the effective parameters of porous media containing mesoscopic inhomogeneities. As an important application of the double-porosity dual-permeability (DPDP) model, I have reformulated the effective Biot model using the total-field variables. This gives rise to new and more general governing equations than the previous approach based on the host phase field variables (which become a special case of the more general treatment). The analytical transient solution and dispersion characteristics for the double-porosity model and also for a poro-viscoacoustic model are derived over the entire frequency range for a homogeneous medium. The comparison between the results of the two models shows that dissipation by local mesoscopic flow of the double porosity model is very hard to fit by a single Zener element over a broad band. I chose the relaxation function to approximate the dispersion behaviour of the double porosity model just around the source centre frequency. It is shown that for most water-filled sandstones having a double porosity structure, wave propagation can be well described by the poro-viscoaoustic model with a single Zener element in the seismic frequency range. The transient solution for heterogeneous double porosity media is obtained by a numerical pseudospectral time splitting technique. This method is extended to 2.5-D poro-viscoelastic media to capture both P and S wave behaviour. I also demonstrate that if the frequency is below several Hz, then a single Kelvin-Voigt element gives an even better result than a single Zener element. I propose a two-phase permeability spherical inclusion model and obtain the dispersion curves of phase velocity and dissipation factor for the composite. I then determine the effective dynamic permeability of porous media with mesoscopic heterogeneities over the whole frequency range. This result is used to check the validity of other measures of effective dynamic permeability, deduced from the effective hydraulic permeability by replacing the permeability of the components with their dynamic values as determined from the Johnson, Koplik and Dashen (JKD) model. I also investigate the scattering of plane transverse waves by a spherical porous inclusion embedded in an infinite poroelastic medium. The vector displacement wave equations of Biot’s theory are solved as an infinite series of vector spherical harmonics for the case of a plane S-wave incidence. Then, the non-self-consistent theory is used to derive the dispersion characteristics of shear wave velocity and attenuation for a porous rock having mesoscopic spherical inclusions which are designed to represent either the patchy saturation model or the double porosity model with dilute concentrations of identical inclusions. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1457632 / Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2009

This thesis documents the work undertaken to investigate and improve the theoretical and practical requirements for two-dimensional hydrodynamic modelling of coastal and estuarine areas, in particular to the inter-related aspects of: - wetting and drying of relatively large intertidal areas, and - the influences of waves on both current generation and variations in mean water level. The work outlined in this thesis began as a result of a perceived lack of understanding and confidence in the application of finite element models to coastal and estuarine situations. In response to this observation an investigation into the modelling parameters, particularly those that affect model performance during the simulation of wetting and drying, was undertaken. This initial investigation into the effect of these parameters upon model performance forms the first component of this study. Testing was performed to provide a quantitative assessment of the effect of these parameters upon model performance. The initial tests were simple examples designed to investigate the behaviour of a single specific parameter. Subsequent tests were more complex and assessed the combinations of various parameter selections. Once the model was shown to accurately simulate the movement of waters in a coastal and estuarine environment, wave forces were incorporated. The aim of the second component of the study was to modify the hydrodynamic model to predict the net current and water levels attributable to the influences of waves. Tests examined the effects of the application of wave induced forces in a range of applications, including the simple case of a uniform beach, comparisons to a physical model, and an example from a real coastline. The final outcome of this study is the development of a modelling tool that can accurately represent the forces of tides, winds and waves upon water movement in a shallow coastal and/or estuarine region. Furthermore, the qualitative and quantitative assessments of parameters that affect the performance of the model provide greater confidence in model results and better understanding of the applicability and limits of the modelling technique. Principal outcomes of the study are: - an improved understanding of the parameters which influence the behaviour of hydrodynamic models; - a better understanding of the applicability and limits of the modelling technique; and - an enhanced software system based on an existing modelling software system which is applicable to studies that require simulation of the combined forces of tides, winds and waves.

Thesis (M. App. Sc.)--Carleton University, 2003. / Includes bibliographical references (p. 182-187). Also available in electronic format on the Internet.

Thesis (M.Sc.) - Carleton University, 2004. / Includes bibliographical references. Also available in electronic format on the Internet.