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The main area of study of this thesis was to research the effect of the bathymetry (the topography of the ocean floor) on the turbulent nature of a tidal energy site by way of high-resolution computational fluid dynamics simulations. Wall Modelled Large Eddy Simulations, for both flood and ebb tides, were carried out of a sampled area of the Fall of Warness, Scotland, which is the European Marine Energy Centre tidal energy site. Results from the simulations were validated with velocity and turbulence data from site measurements at the European Marine Energy Centre site. Both the simulation and the test data correspond to flows at 2.1 m/s turbine hub height reference velocity for ebb and flood tides. Results show the influence of the sea bottom as a modifier of flow velocities and a driver of turbulence production at local areas important for the purposes of tidal converter performance and loading. High order turbulence parameters such as: Reynolds stresses, length scales, frequency spectra and turbulence intensities are analysed at different depths and locations in the domain, to better understand their local dependence on the changing bathymetry. Turbulence data presents highly energetic coherent structures of a sufficiently large spatial and temporal size, connected to bathymetry variation. Both flood and ebb tidal simulations show that site bathymetry not only influences the mean flow, but also turbulent structure, energy efficiency of turbulent kinetic energy extracted from wall shear stress and three-dimensional distribution of Reynolds Stresses. Turbulence was found to be more isotropic for larger portions of the water column than found in previous simulations of roughened surface flows, with an especially chaotic flow area covering the bottom fifth of the water column filled with energy rich turbulent events. Quadrant analysis for multiple depth probe locations is used to give a three-dimensional statistical understanding of bursting events, as modified by the seabed. The results show highly energetic coherent structures of a sufficiently large spatial and temporal size, connected to bathymetry variation. Ebb and flood turbulent features were compared in an effort to further understand the role bathymetry plays on tidal asymmetry. The temporal, spatial and energetic character of coherent turbulent structures were analyzed, within a context of the direction of the flow and its link to the seabed as a driving force for turbulence generation. Ebb tide was found to have a stronger turbulent intensity and production than flood tide for the same reference mean flow velocities. The thesis adds to the knowledge of tidal energy site flow characterization and the turbulence of offshore environments by showing the strong imprint of bathymetry on tidal flows. The numerical methodology employed shows a guideline for studying the local and unique seabed bathymetry interactions with the tides. The use of high-resolution large eddy simulations is shown to be a tool capable of reproducing energy rich resolved structures vital to continuous advancement of energy extraction devices.

Most realistic fluid flow problems are characterised by high Reynolds numbers and complex boundaries. Over the last ten years, immersed boundary methods (IBM) that are able to cope with realistic geometries have been applied to Lattice- Boltzmann methods (LBM). These methods, however, have normally been applied to low Reynolds number problems. In the present work, an iterative direct forcing IBM has been successfully coupled with a multi-domain cascaded LBM in order to investigate viscous flows around rigid, moving and wilfully deformed boundaries at a wide range of Reynolds numbers. The iterative force-correction immersed boundary method of (Zhang et al., 2016) has been selected due to the improved accuracy of the computation, while the cascaded LB formulation is used due to its superior stability at high Reynolds numbers. The coupling is shown to improve both the stability and numerical accuracy of the solution. The resulting solver has been applied to viscous flow (up to a Reynolds number of 100000) passed a NACA-0012 airfoil at a 10 degree angle of attack. Good agreement with results obtained using a body-fitted Navier-Stokes solver has been obtained. At moving or deformable boundary applications, emphasis should be given on the influence of the internal mass on the computation of the aerodynamic forces, focusing on deforming boundary motions where the rigid body approximation is no longer valid. Both the rigid body and the internal Lagrangian points approximations are examined. The resulting solver has been applied to viscous flows around an in-line oscillating cylinder, a pitching foil, a plunging SD7003 airfoil and a plunging and flapping NACA-0014 airfoil. Good agreement with experimental results and other numerical schemes has been obtained. It is shown that the internal Lagrangian points approximation accurately captures the internal mass effects in linear and angular motions, as well as in deforming motions, at Reynolds numbers up to 4 • 104. Finally, an expanded higher-order immersed boundary method which addresses two major drawbacks of the conventional IBM will be presented. First, an expanded velocity profile scheme has been developed, in order to compensate for the discontinuities caused by the gradient of the velocity across the boundary. Second, a numerical method derived from the Navier-Stokes equations in order to correct the pressure distribution across the boundary has been examined. The resulting hybrid solver has been applied to viscous flows around stationary and oscillating cylinders and examined the hovering flight of elliptical wings at low Reynolds numbers. It is shown that the proposed scheme smoothly expands the velocity profile across the boundary and increases the accuracy of the immersed boundary method. In addition, the pressure correction algorithm correctly expands the pressure profile across the boundary leading to very accurate pressure coefficient values along the boundary surface. The proposed numerical schemes are shown to be very efficient in terms of computational cost. The majority of the presented results are obtained within a few hours of CPU time on a 2.8 GHz Intel Core i7 MacBook Pro computer with a 16GB memory.

Probiotics are certain living microorganisms that have to be in the human body for health benefits. The administration of probiotics can treat different metabolic disorders and other health issues. Bacteria are sensitive to their environment. The viability of probiotics is affected by adverse conditions such as pH and temperature. Probiotic delivery can be in different modes. Nowadays, food products containing probiotic mixtures are of great interest by conumers. These products are for the administration of probiotics to improve the gut microflora. Oral administration of probiotics can improve not only the gut health, but it is a holistic approach of health improvement also. The immunomodulation ability of probiotics is beneficial for treatments of a number disorders and skin improvement. Objective of this research was to study the effects of a novel food gel(NG) on the viability of Lactobacillus acidophilus and antimicrobial activity against acne causing bacteria Propionibacterium acnes. An acne treatment ointment had taken as a control to compare the microbial analysis. The results showed, a negative effect of gel on the viability of Lactobacillus acidophilus, but a positive result was obtained for the antimicrobial activity of gel against Propionibacterium acnes. The flow characteristics were depended on the temperature and was suitable for a topical gel formulation. Further studies must be done for formulate new food gel as a topical acne treatment ointment.

Abstract withheld due to embargo restriction

Abstract: Increasingly, human activities for the societal development and quality of life can alter, disrupt or destroy aquatic habitat with varying degrees. The rising awareness and concern regarding such type of human activities on stream and riverine ecosystem have resulted in a movement towards habitat compensation to achieve no net loss in productive capacity of fish habitat. As part of a fish habitat compensation project, this thesis investigated detailed flow characteristics in small northern streams and in rock-ramp type nature-like fishpasses through field, laboratory, and numerical studies. The principal motivation for this study is to advance our understanding of flow characteristics in a rock-ramp fishpass to retrofit small streams for fish habitat connectivity and compensation. First, the flow characteristics of a headwater stream as a fish migration corridor and the hydraulic characteristics of several headwater streams in the Northwest Territories of Canada were investigated. The analysis of stream hydrological or hydraulic flow characteristics demonstrated that some sections of the study stream for certain durations of the study period appeared to naturally provide suitable habitat for select stages of YOY (young-of-the-year) Arctic grayling, while other sections would require certain modifications and additional outlet flow arrangements. The study of hydraulic characteristics explored the nature of at-a-station hydraulic geometry and flow resistance in an unstudied geographic region of the Northwest Territories of Canada for the future habitat assessment and predictions. Next, detailed mean and turbulence flow characteristics generated by a staggered arrangement of boulders in a rock-ramp nature-like fishpass were investigated experimentally. The results showed that this type of fishpass can produce adequate water depth and favorable flow velocity, turbulent intensity, and turbulent kinetic energy for suitable fish passage. Some general correlations were developed for predicting the mean and turbulence flow parameters in a rock-ramp fishpass as a function of normalized discharge and streamwise distance. Moreover, a flow resistance analysis based on basic concepts for wake-interference flow regime in this fishpass has resulted in a general equation for the average velocity. Finally, a three-dimensional Computational Fluid Dynamics (CFD) solver was used to investigate the flow characteristics in a rock-ramp nature-like fishpass under different flow conditions and geometric variables. The model was validated with experimental data and a good agreement was achieved. The findings emanating from this numerical study optimized the design of rock-ramp fishpasses.

Computational analysis along with extensive experimental investigation have been carried out to predict drag reduction in slug flow utilizing three types of oil with viscosities of 2.5 cP, 26 cP, and 50 cP in 10-cm ID, horizontal and 2-degree inclined pipes. Effects of oil viscosity and pipe inclination on each component of the total pressure drop in slug flow were determined. The impact of liquid viscosity and pipe inclination on the effectiveness of drag reducing agents (DRA) was also investigated. Predicted values were in good agreement with experimental results. Results from both experiments and modeling showed that the accelerational component of pressure drop was dominant in low and moderate oil viscosities. This component reached values as high as 86% of total pressure drop. Most of the drag reduction took place in the accelerational component and reached values as high as 88% out of total drag reduction. As oil viscosity increased, the frictional component was found to increase dramatically and exceeded 40% of total pressure drop in the 50 cP oil. The DRA was found more effective in reducing both frictional and gravitational components of total pressure drop in higher-viscosity oils than in lower ones. For example, at superficial liquid and gas velocities of 0.5 and 6 m/s frictional loss was reduced by a factor of 60% in the 26 cP oil when adding 50 ppm of the DRA. The corresponding value for the 2.5 cP oil was less than 10%. Meanwhile, the DRA was more effective in reducing accelerational component, hence total pressure drop, in the 2.5 cP oil than in the 26 cP oil. Pressure drop increased significantly when pipe inclination was changed from horizontal to 2 degrees due to the presence of the gravitational component. This increase in pipe inclination was accompanied with a decrease in the velocity of the stratified film ahead of each slug. Thus resulting in an elevated accelerational pressure loss. This work will help introduce new mechanisms for drag reduction in multiphase flow and provide a new mechanistic or empirical correlation to incorporate drag reduction in multiphase flow.

Effects of drag reducing agents on pressure drop and flow characteristics in multiphase inclined pipelines

The linear stability analysis of Huang [1995] has been adapted to ignore the effects of swirl, and to allow calculation of the eigenvalues and eigenfunctions for integer, fractional, and multiple modes of excitation. The investigation was intended to be exploratory; to gain the best possible insights into the flow characteristics from analysis of the linearized Euler equations. All of the azimuthal modes investigated (one-half, one, three-halves, and two) were found to lead to the continuous, helical, vortical structure evolution in the streamwise direction of the jet. The analysis for fractional modes of excitation predicted aphysical behavior near the jet center that has been attributed to a unresolved questions in the mathematical analysis of the problem. Multiple mode excitation at the axisymmetric mode and one or more azimuthal modes were found to result in un-even, periodic, vortex-ring growth in the shear layer. An argument was presented for the axisymmetric mode (m=O) resulting in the highest levels of entrainment for all integer, fractional, and multiple modes of excitation. Finally the importance of the azimuthal component of vorticity in the entrainment process was identified.

A review of the theory of the shear testing of granular materials is given, together with a discussion of the requirements for test specimens and equipment. The theory of the annular cell is also reviewed and a computer programme to solve the Hvorslev equation for true stress is developed. The physical properties and yield loci for fourteen instantaneously compacted granular superphosphate samples are presented. Stresses calculated on the assumption of uniform strain were within 5% of the true stress. No significant regression existed between the shear stress during compaction and that during the test which followed it. The flow characteristics of samples representing approximate extremes in particle size and maturity indicate that these materials are free flowing.