Thesis (M.A.)--Kent State University, 2009. / Title from PDF t.p. (viewed Jan. 12, 2010). Advisor: Gina Zavota. Keywords: Aristotle, ancient physics, place, unity, Benjamin Morison. Includes bibliographical references (p. 129-132).

Converting energy from ocean waves is an exciting concept aimed at reducing our dependency on fossil fuels. Ocean energy devices must convert the large forces and relatively small movements from ocean waves into electrical power with a minimum carbon and energy intensity in order to be economically viable. The research herein focuses on the Oyster, a flap-type pitching wave energy converter developed by Aquamarine Power. A device that has the minimal carbon or energy intensity is not necessarily the most mechanically efficient. A commercially viable wave energy converter should have a competitive cost of energy and be as carbon negative as possible. In order to expedite the route to commercialisation, successive designs should iterate towards a minimum lifetime cost of energy. The sheer complexity of wave energy converter systems makes for a vast optimisation problem to determine the system parameters that exhibit the minimum carbon and energy intensities. This thesis presents a study of the oscillating flap-type wave energy converter to determine the trends between design parameters, total power output and carbon and energy throughput. The minimum carbon and energy intensities have been shown to be strongly dependent on minimising maintenance requirements. In order to determine the design criterion a range of flap widths and system pressures are investigated and their effect on component service lives assessed. The results are then converted to lifetime carbon and energy intensities for a direct comparison. To achieve this, fundamental research on the maintenance requirements of critical components such as the hinge bearings and hydraulic power system is required. A hydrodynamic model describes the dynamic response and links the system energy inputs to its modelled energy output. This work is intended to help guide developers of flap-type wave energy converters towards commercialisation. It enhances the understanding of the routes to failure and service life predictions, providing avenues to balance service lives to optimise maintenance and maximise uptime. This will assist in the development of more energy efficient wave energy converters over their lifetime. This information will better enable the marine energy sector to offset our fossil fuel dependence, ultimately reducing our impact on the environment and leading to a ‘greener’ future.

In the present study, the influence of geometric scale, unit orientation (alternatively, flow direction), and the dimensionless Reynolds and Keulegan-Carpenter quantities on the hydrodynamic loading of Core-Loc armour units is explored through a series of physical modelling tests under unsteady and oscillatory flow conditions.

No description available.

No description available.

Um corpo imerso em movimento arbitrário interage com o fluido ao redor. As partículas fluidas próximas ao corpo exercem certa resistência inercial quando o corpo acelera ou desacelera, devido ao acoplamento dinâmico entre corpo e fluido. Este trabalho resolve as equações de Navier-Stokes, discretizadas pelo método dos elementos finitos, usando o programa de código aberto (LGPL) FreeFem++, e avalia as forças do escoamento que agem sobre um cilindro circular, o qual oscila harmonicamente em um fluido em repouso para números de Keulegan-Carpenter (KC) entre 0,5 e 10, mantendo o parâmetro da frequência constante e igual a 35. Os números de KC selecionados visam entender os conceitos de inércia adicional em fluido viscoso, desde em escoamentos simples até em escoamento mais complexos. O escoamento é bidimensional, laminar e não estacionário. A força em linha com o movimento é então decomposta, conforme equação de Morison, como a soma de uma força inercial e outra de arrasto. Os resultados possuem boa aderência com trabalhos analíticos, experimentais e numéricos anteriores disponíveis na literatura. A dinâmica do escoamento induzido pelo cilindro em movimento harmônico é rica. Para baixo KC, o escoamento é simétrico e estável. Para valores intermediários de KC, a camada limite descola da superfície do cilindro e vórtices são emitidos a cada meio-ciclo. Para elevado KC, certa assimetria se desenvolve e vórtices são emitidos obliquamente a cada meio-ciclo. / An immersed body in arbitrary motion interacts with the surrounding fluid. The fluid particles close to the body impart their inertial resistance when the body accelerates or decelerates, due to the dynamic coupling between body and fluid. This work solves the incompressible Navier-Stokes equation, discretized by the finite element method, using the open source (LGPL) software FreeFem++, and evaluates the flow forces that act on a circular cylinder which oscillates harmonically in a resting fluid for Keulegan- Carpenter (KC) number between 0.5 and 10, with a constant frequency parameter equal to 35. The selected KC numbers aims to understand the concepts of added inertia in viscous fluid, from simpler to more complex flows. The flow is two dimensional, laminar and unsteady. The in-line force is then decomposed, according to Morison equation, as a sum of an inertial force and a drag force. The results agree with former analytical, experimental and numerical works available in the literature. The dynamics of the flow induced by the harmonically moving cylinder is rich. For low KC, the flow is symmetric and stable. For intermediate KC, the boundary layer detaches from the cylinder surface and vortices are shed at each half cycle. For higher KC, certain asymmetry develops and vortices are shed obliquely at each half cycle.

Um corpo imerso em movimento arbitrário interage com o fluido ao redor. As partículas fluidas próximas ao corpo exercem certa resistência inercial quando o corpo acelera ou desacelera, devido ao acoplamento dinâmico entre corpo e fluido. Este trabalho resolve as equações de Navier-Stokes, discretizadas pelo método dos elementos finitos, usando o programa de código aberto (LGPL) FreeFem++, e avalia as forças do escoamento que agem sobre um cilindro circular, o qual oscila harmonicamente em um fluido em repouso para números de Keulegan-Carpenter (KC) entre 0,5 e 10, mantendo o parâmetro da frequência constante e igual a 35. Os números de KC selecionados visam entender os conceitos de inércia adicional em fluido viscoso, desde em escoamentos simples até em escoamento mais complexos. O escoamento é bidimensional, laminar e não estacionário. A força em linha com o movimento é então decomposta, conforme equação de Morison, como a soma de uma força inercial e outra de arrasto. Os resultados possuem boa aderência com trabalhos analíticos, experimentais e numéricos anteriores disponíveis na literatura. A dinâmica do escoamento induzido pelo cilindro em movimento harmônico é rica. Para baixo KC, o escoamento é simétrico e estável. Para valores intermediários de KC, a camada limite descola da superfície do cilindro e vórtices são emitidos a cada meio-ciclo. Para elevado KC, certa assimetria se desenvolve e vórtices são emitidos obliquamente a cada meio-ciclo. / An immersed body in arbitrary motion interacts with the surrounding fluid. The fluid particles close to the body impart their inertial resistance when the body accelerates or decelerates, due to the dynamic coupling between body and fluid. This work solves the incompressible Navier-Stokes equation, discretized by the finite element method, using the open source (LGPL) software FreeFem++, and evaluates the flow forces that act on a circular cylinder which oscillates harmonically in a resting fluid for Keulegan- Carpenter (KC) number between 0.5 and 10, with a constant frequency parameter equal to 35. The selected KC numbers aims to understand the concepts of added inertia in viscous fluid, from simpler to more complex flows. The flow is two dimensional, laminar and unsteady. The in-line force is then decomposed, according to Morison equation, as a sum of an inertial force and a drag force. The results agree with former analytical, experimental and numerical works available in the literature. The dynamics of the flow induced by the harmonically moving cylinder is rich. For low KC, the flow is symmetric and stable. For intermediate KC, the boundary layer detaches from the cylinder surface and vortices are shed at each half cycle. For higher KC, certain asymmetry develops and vortices are shed obliquely at each half cycle.

No description available.

The aim of this master thesis is to characterize the fluid forces applied to a fuel assembly inthe core of a nuclear power plant in case of seism. The forces are studied with a simplifiedtwo-dimensional model constituted of an array of 3 by 3 infinite cylinders oscillating in aclosed box. The axial flow of water, which convects the heat in the core of a nuclear powerplant, is also taken into account. The velocity of the axial flow reaches 4m/s in the middle ofthe assembly and modifies the forces features when the cylinders move laterally.The seism is modeled as a lateral displacement with high amplitude (several cylinderdiameters) and low frequencies (below 20 Hz). In order to study the effects of the amplitudeand of the frequency of the displacement, the displacement taken is a sine function withboth controlled amplitude and frequency. Four degrees of freedom of the system will bestudied: the amplitude of the displacement, its frequency, the axial velocity amplitude andthe confinement (due to the closed box).The fluid forces exerted on the cylinders can be seen as a combination of three terms: anadded mass, related to the acceleration of cylinders, a drift force, related to the damping ofthe fluid and a force due to the interaction of the cylinder with residual vortices. The firsttwo components will be characterized through the Morison expansion, and their evolutionwith the variation of the degree of freedom of the system will be quantified. The effect ofthe interaction with the residual vortices will be observed in the plots of the forces vs. timebut also in the velocity and vorticity map of the fluid.The fluid forces are calculated with the CFD code Code_Saturne, which uses a second orderaccurate finite volume method. Unsteady Reynolds Averaged Navier Stokes simulations arerealized with a k-epsilon turbulence model. The Arbitrary Lagrange Euler model is used todescribe the structure displacement. The domain is meshed with hexahedra with thesoftware gmsh [1] and the flow is visualized with Paraview [2]. The modeling techniquesused for the simulations are described in the first part of this master thesis.

During the twentieth century, Cable & Wireless was the world’s biggest and most important telegraphy company, employing large numbers of people in stations across the world. Its network of submarine cables and wireless routes circumnavigated the globe, connecting Britain with the Empire. This thesis examines the ways in which the British Empire and modernity shaped Cable & Wireless’ corporate identity in order to understand the historical geography of the relationships between Empire, state, and modernity. Additionally, it investigates the role of design in the Company’s engagement with the discourses of modernity and imperialism. Historical Geography has not paid sufficient attention to the role of companies, in particular technology companies, as institutions of imperialism and instruments of modernity. The study of businesses within Historical Geography is in its infancy, and this thesis will provide a major contribution to this developing field. This thesis takes an interdisciplinary approach that sits at the intersection of three main disciplines: Historical Geography, Design History and Business History. This thesis examines how Cable & Wireless’ identity was produced, transmitted and consumed. This thesis is based on detailed research in Cable &Wireless’ corporate archive at Porthcurno, examining a wide range of visual and textual sources. This pays particular attention to how the Company designed its corporate identity through maps, posters, ephemera, corporate magazines and exhibitions. Drawing upon the conceptualizations of the Empire as a network, it argues that Cable & Wireless’ identity was networked like its submarine cables with decision-making power, money and identity traversing this network. This thesis seeks to place both the company and the concept of corporate identity within a broader historical and artistic context, tracing the development of both the company’s institutional narrative and the corporate uses of visual technologies. No study has been conducted into the corporate identity and visual culture of Cable & Wireless. This thesis not only provides a new dimension to knowledge and understanding of the historical operations of Cable & Wireless, but also makes a substantive contribution to the wider fields of Historical Geography, Business History, Design History and the study of visual culture.