The South China Sea is a marginal basin with a complex circulation influenced by the East Asian Monsoon, river discharge and intricate bathymetry. As a result, both the mesoscale eddy field and the near-inertial energy distribution display large spatial variability and they strongly influence the oceanic transport and mixing. With an ensemble of numerical integrations using a regional ocean model, this work investigates how the temporal resolution of the atmospheric forcing fields modifies the horizontal and vertical velocity patterns and impacts the transport properties in the basin. The response of the mesoscale circulation in the South China Sea is investigated under three different forcing conditions: monthly, daily and six-hourly momentum and heat fluxes. While the horizontal circulation does not display significant differences, the representation of the vertical velocity field displays high sensitivity to the frequency of the wind forcing. If the wind field contains energy at the inertial frequency or higher (daily and six-hourly cases), then Vortex Rossby waves and near inertial waves are excited as ageostrophic expression of the vigorous eddy field. Those waves dominate the vertical velocity field in the mixed layer (vortex Rossby waves) and below the first hundred meters (near inertial waves) and they are responsible for the differences in the vertical transport properties under the various forcing fields as quantified by frequency spectra, vertical velocity profiles and vertical dispersion of Lagrangian tracers.

Thesis (M.S.) -- Mississippi State University. Department of Computational Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 125-128) / Microfiche. / xii, 128 leaves, bound ill. 29 cm

CD-ROM containing source codes of the numerical scheme (appendix A) is attached to back cover. / Includes bibliographical references (leaves 459-472). / System requirements for accompanying CD-ROM: Macintosh or IBM compatible computer. Other requirements: Adobe Acrobat Reader. / xxxvi, 473 leaves ; ill. ; 30 cm. + 1 computer optical disk (4 3/4 in.) / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A numerical scheme, based on discrete-vortex and surface-vorticity boundary-integral methods, has been developed for stimulating time dependent, two-dimensional, viscous flow over arbitary arrays of solid bodies of arbitary cross-section / Thesis (Ph.D.)--Adelaide University, Dept. of Mechanical Engineering, 2001

[Truncated abstract] The subject of fan noise generating mechanisms and its control has been studied intensively over the past few decades as a result of the ever-increasing demand for more powerful fans. A unique feature of fan noise is that it consists of high-level discrete frequency noise related to the blade passing frequency, and low-level broadband noise due mostly to turbulent airflow around the fan. Of the two types of fan noise, the discrete frequency noise is the more psychologically annoying component. Past research into fan noise has shown that the discrete frequency fan noise are dipole in nature and are caused predominantly by the fluctuating lift acting on the surfaces of the fan blades. Based on this, several theoretical models have been established to correlate these fluctuating lift forces to the far-field sound pressure. However, one general assumption in these models is that the fan blades are assumed rigid, and the consequence of such an assumption is that it is unclear if the far-field sound pressure is caused solely by the aerodynamic lift force, or whether the blade vibration also plays a substantial role in the generation of the far-field fan noise. One of the goal of this thesis was thus to experimentally quantify the contribution of blade vibration to far-field fan noise and it was found that blade vibration, whilst coherent with the far-field fan noise, did not contribute significantly. Aside of this, several experiments aimed at filling knowledge gaps in the understanding of fan noise characteristics were also be conducted, in particular, to understand the relationship between far-field sound pressure level to blade lengths as well as the number of blades on the fan. The experiments showed that for fans with many blades, the dependency of the far-field sound pressure on blade length is stronger than fans with less blades. Furthermore, dipole measurements showed that the dipole characteristics of fan noise does not occur only at the discrete frequencies, but also within a range of broadband frequencies, implying that the source for both discrete and broadband is the same. The second section of this thesis deals with the study of vortex shedding and its active control. When a circular cylinder (or any object) is placed in a flow within a specified Reynolds number range, flow separation and periodical wake motion is formed behind the cylinder, which is known as vortex shedding. It has been found in previous research that this wake motion is affected by acoustic field imposed on it via loudspeakers. This suggests that there is a strong acoustic-vortex relationship. However, little of this relationship is understood as conventional methods of studying vortex centre around the use of hot-wire anemometry, which effectively measures the velocity fluctuation in the flow. This thesis is the first in using a microphone to study the acoustic characteristic of the vortex wake, and experimental results shows that the two parallel shear layers of the wake carry the strongest pressure signals at the vortex shedding frequency, whilst the entrapped region between the layers carries the strongest pressure signals at the first harmonic.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 202-207).

Thesis (Ph.D.)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: leaf 208-224.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 224-244). Also available in electronic format on the Internet.

Orientador: Isaias Vizotto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-24T02:40:36Z (GMT). No. of bitstreams: 1 Ferreira_AntonioMario_D.pdf: 9010854 bytes, checksum: 0b548385f37faa810cae541ae265ec42 (MD5) Previous issue date: 2013 / Resumo: Este trabalho realiza uma análise numérica e experimental do comportamento de estruturas em cascas de formas livres sob a ação do vento. Inicialmente foram gerados modelos computacionais de formas otimizadas, sendo uma casca de planta pentagonal e outra hexagonal. Na sequência foram construídos modelos físicos reduzidos em laboratório e submetidos a uma série de ensaios em túnel de vento. E, finalmente foram realizadas simulações numéricas dessas estruturas submetidas à ação do vento utilizando o programa computacional ANSYS-CFX do Laboratório de Informática da FEC-UNICAMP. Os modelos físicos reduzidos analisados foram gerados utilizando o software ANSYS e o programa computacional desenvolvido por Vizotto (1993), e construídos no Laboratório de Automação e Prototipagem para Arquitetura e Construção (LaPAC) da FEC-UNICAMP, utilizando inicialmente isopor de alta densidade, que foi posteriormente empregado para execução de fôrmas de concreto armado para moldar os modelos finais em material composto por fibra de vidro e resina, para serem ensaiados no túnel de vento do Laboratório de Conforto Ambiental e Física Aplicada (LaCAF) da FEC-UNICAMP. Os testes no túnel de vento do LaCAF foram realizados em dezesseis fases, sendo compostas por análises para obtenção dos coeficientes de pressão externa e interna, com ventos em regime laminar e turbulento, a 0º e 36º para a casca com forma de planta pentagonal, e a 0º e 30º para a casca com forma de planta hexagonal. Para análises por meio de simulação fluidodinâmica computacional pelo ANSYS-CFX, foi realizada inicialmente uma análise comparativa para os resultados dos coeficientes de pressões externas de um modelo de cúpula sobre o terreno da NBR 6123:1988. O software ANSYS-CFX demonstrou ótima eficiência na configuração realizada, apresentando resultados muito próximos aos da norma brasileira, e essa configuração também foi utilizada na validação física entre os ensaios no túnel de vento e as simulações pelo ANSYS-CFX. É sugerida a utilização dos dados finais na elaboração de normas específicas e uma configuração adequada e segura dentro das características consideradas para a utilização do software ANSYS-CFX como ferramenta para obtenção de coeficientes de pressões / Abstract: This work performs a numerical and experimental analysis of behavior of structures in free form shells about wind action. At first, computational models were generated in optimized forms, being one shell of pentagonal shape and another one hexagonal. After this, reduced physical models were built in laboratory and subjected to several tests in the tunnel of wind. Finally, numerical analyzes of these structures subjected to wind action were achieved using ANSYS computational program from FEC-UNICAMP computer laboratory. Two reduced physical models were analyzed, using the software ANSYS and the computational program that was developed by VIZOTTO I. (1993), and built at the Laboratory of Automation and Prototyping for Architecture and Construction site (LaPAC) from FECUNICAMP. The techniques: one hexagonal and another pentagonal, both made, at first, with Styrofoam in large dense, that was applied to execution of forms of concrete to be sculptured and finalized as a material composed of glass fiber and resin for future test in the wind tunnel at (LaCAF) from FEC-UNICAMP Environmental Comfort and Applied Physics Laboratory. The tests at the wind tunnel from LaCAF were made into sixteen phases, composed by analysis to obtain the coefficients of outside and inside pressure with wind in turbulent and laminar state, at 0º and 30º for hexagonal shape and turbulent and laminar, at 0º and 36º for pentagonal shape. To analyze by simulation computational fluid dynamics by ANSYS-CFX, at first were achieved a comparative analysis to the results of coefficients of outside pressure from a model of dome on the land from NBR 6123:1980. The software ANSYS-CFX showed an excellent efficiency on the made configuration, showing results very closed to the Brazilian rule, and this configuration also was used in the physical validation between the tests at wind tunnel and the simulations by ANSYS-CFX. It is suggested the usage of final data on specific standard preparation and safe configuration for ANSYS software application as a tool to achieve pressure coefficients / Doutorado / Estruturas / Doutor em Engenharia Civil

The density amplitude of an isolated quantum vortex line in superfluid 4He is calculated using a generalized Gross-Pitaevskii (G-P) equation. The generalized G-P equation for the order parameter extends the usual mean-field approach by replacing the interatomic potential in the ordinary G-P equation by a local, static T matrix, which takes correlations between the particles into account. The T matrix is a sum of ladder diagrams appearing in a diagrammatic expansion of the mean field term in an exact equation for the order parameter. It is an effective interaction which is much softer than the realistic interatomic Morse dipole-dipole potential from which it is calculated. A numerical solution of the generalized G-P equation is required since it is a nonlinear integro-differential equation with infinite limits. For the energy denominator in the T matrix equation, a free-particle spectrum and the observed phonon-roton spectrum are each used. For the fraction of particles in the zero-momentum state (Bose-Einstein dondensate) which enters the equation, both a theoretical value of 0.1 and an experimental value of 0.024 are used. The chemical potential is adjusted so that the density as a function of distance from the vortex core approaches the bulk density asymptotically. Solutions of the generalized G-P equation are not very dependent on the choice of energy denominator or condensate fraction. The density profile is a monotonically increasing function of the distance from the vortex core. The core radius, defined to be the distance to half the bulk density, varies from 3.7 A to 4.7 A, which is over three times the experimental value of 1.14 A at absolute zero.