Two dimensional experimental and numerical modeling of wave transmission and wave-induced current over detached submerged breakwaters has been carried out in this thesis. Two preliminary 3D and a comprehensive series of 2D laboratory experiments have been conducted in the wave basin and 3 m wide wave flume. The preliminary 3D experimental tests qualitatively investigated the flow behavior behind a submerged breakwater and confirmed the validity of the 2D tests. The 2D laboratory tests examined wave breaking, reflection, transmission as well as wave-induced set-up and currents over submerged breakwater/reef structures. Different approaches to experimental data processing are examined in producing reliable application of the 2D laboratory measurements. Sensitivity of wave transmission coefficient, wave-induced set-up and wave-induced discharge over submerged breakwaters to other dimensional and non-dimensional parameters are comprehensively investigated. Previously published analytical/experimental studies for predicting/calculating wave breaking, wave transmission, wave-induced set-up and current are discussed and compared with the present experimental results. Improved equations/models are presented. Numerical modeling of the hydrodynamic effects of wave breaking and flow over a submerged breakwater is investigated using Delft3D. The capability of the Delft3D numerical model to simulate wave height transformation and wave-induced current over submerged breakwaters is provided. Four different approaches using combinations/options within the two main modules of Delft3D (SWAN and FLOW) are tested in the numerical simulations and the results are compared to the laboratory experimental data. Guidance is provided as to the most appropriate application of WAVE/FLOW/ROLLER modules in Delft3D for the reliable prediction of discharge and wave height over different width submerged breakwaters.

Two dimensional experimental and numerical modeling of wave transmission and wave-induced current over detached submerged breakwaters has been carried out in this thesis. Two preliminary 3D and a comprehensive series of 2D laboratory experiments have been conducted in the wave basin and 3 m wide wave flume. The preliminary 3D experimental tests qualitatively investigated the flow behavior behind a submerged breakwater and confirmed the validity of the 2D tests. The 2D laboratory tests examined wave breaking, reflection, transmission as well as wave-induced set-up and currents over submerged breakwater/reef structures. Different approaches to experimental data processing are examined in producing reliable application of the 2D laboratory measurements. Sensitivity of wave transmission coefficient, wave-induced set-up and wave-induced discharge over submerged breakwaters to other dimensional and non-dimensional parameters are comprehensively investigated. Previously published analytical/experimental studies for predicting/calculating wave breaking, wave transmission, wave-induced set-up and current are discussed and compared with the present experimental results. Improved equations/models are presented. Numerical modeling of the hydrodynamic effects of wave breaking and flow over a submerged breakwater is investigated using Delft3D. The capability of the Delft3D numerical model to simulate wave height transformation and wave-induced current over submerged breakwaters is provided. Four different approaches using combinations/options within the two main modules of Delft3D (SWAN and FLOW) are tested in the numerical simulations and the results are compared to the laboratory experimental data. Guidance is provided as to the most appropriate application of WAVE/FLOW/ROLLER modules in Delft3D for the reliable prediction of discharge and wave height over different width submerged breakwaters.

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Although more emphasis is being placed on African Americans athletes, there are still disparities in the number of African American athletes compared to the number of African Americans in administrative positions. This study is based on the argument that supports the need for more African American in athletic administration positions, by examining the current hiring and retention of African American administrators and the critical issues underlying their employment.It is important to have more information readily available since there is such a large percent of African American athletes competing at institutions. Until the number of African American administrators is equitable to the number of participants creating revenue for their respective universities, there will always be a need for this study.This study utilized qualitative research methods to analyze interviews and survey data. The results of this study revealed that having role models, mentors, establishing a network, and enhancing enrollment and graduation rates of African Americans in graduate schools are key elements in increasing the numbers of African Americans in athletic administration positions. / Department of Physics and Astronomy

Thesis (M.E.E.)--University of Delaware, 2007. / Principal faculty advisor: Dennis W. Prather, Dept. of Electrical & Computer Engineering. Includes bibliographical references.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / In this work, we show the initial results of Acousto Optical Tunning Filter in hybrid configuration (HAOTF). This hibrid device have a feedback circuit that connect in SAW can be influence by output in only one mode polarization of the AOTF. Such the croostalk and transmission characteristic of AOTF dependent â output, result in behavior bistable. We analyze the input power by output power in device opering with continuos wave (CW), nonlinear (SPM) and without loss. Obtain the loop of bistability to display the relation between input power and output power considering parameters of AOTF, since: the product among coupling coefficient (κ ) and deviceâs length (ξL ), gain ( G ) and phase mismatching ( ∆β ). / Nesta dissertaÃÃo, apresentamos os resultados de um estudo sobre um AOTF numa configuraÃÃo hÃbrida, caracterizada pela presenÃa de um circuito de realimentaÃÃo. Este circuito de realimentaÃÃo permite que a tensÃo elÃtrica, aplicada ao transdutor (SAW), possa ser influenciada pela potencia de saÃda de uma das polarizaÃÃes do AOTF. Desta forma, a condiÃÃo de casamento de fase (freqÃÃncia de ressonÃncia) e as caracterÃsticas de transmissÃo do AOTF tornam-se dependentes da potencia de saÃda, resultando numa resposta biestÃvel. Inicialmente esta anÃlise consiste em observar a potÃncia do campo incidente pela potÃncia do campo emergente, com o dispositivo operando sob a aÃÃo de uma onda contÃnua no tempo (CW), em regime nÃo linear (SPM) e sem perdas. Neste sentido, obtemos as curvas de biestabilidade, mostrando a relaÃÃo entre as potÃncias de entrada e saÃda, em funÃÃo de diversos parÃmetros do AOTF, como: o produto entre a constante de acoplamento ( κ ) e o comprimento do dispositivo ( ξL ), alÃm do fator de conversÃo potencia - constante de propagaÃÃo de onda ( G ) e do descasamento de fase ( ∆β ).

Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), February 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 327-334). / In the present work, we study the statistics of wavefields obtained from non-linear phase-resolved simulations. The numerical model used to generate the waves models wave-wave interactions based on the fully non-linear Zakharov equations. We vary the simulated wavefield's input spectral properties: directional spreading function, Phillips parameter and peak shape parameter. We then investigate the relationships between a wavefield's input spectral properties and its output physical properties via statistical analysis. We investigate surface elevation distribution, wave definition methods in a nonlinear wavefield with a two-dimensional wavenumber, defined waves' distributions, and the occurrence and spacing of large wave events. / by Legena Albertha Henry. / S.M.

As the second largest river in the U.S., the entrance to the Columbia River is home to some of the most extreme wave conditions on the Pacific Coast. Winter storms commonly generate waves 6-8 m in height, which in combination with strong tidal currents, can produce dangerous navigation conditions. To improve understanding of the wave dynamics in this complex setting, the SWAN model is applied; 2 hindcasts are conducted and an operations forecast is developed. The model is forced with offshore wave heights obtained from a buoy located in 134 m water depth (for the hindcasts) and a specialized WaveWatchIII forecast (for the forecast). In both cases tidal currents are obtained from SELFE, a circulation model of the Columbia River. The hindcasts are validated through measurements obtained from an inshore buoy located in 25 m water depth, a 4-week field experiment and remote sensing methods. The model performs best at the location of the buoy, with a normalized root-mean-squared error (NRMSE) of 11%, primarily because it is outside the area of strong tidal currents. Within the river mouth, the model is able to predict the changes in the wave field due to currents, but its performance is limited by errors in velocity estimates and strong shears in the tidal current profile. From the modeling work, it is evident that wave transformations at the mouth of the river are dominated by the tidal currents. The forecast has been operational since August 2011 and provides 45-hours of predictive wave information. In comparison with measured wave heights at the buoy, the forecast performs well, with a NRMSE of 16%. The majority of errors are caused by errors in the input conditions, since they themselves are forecasted. Additional errors arise from phase-resolved properties in the wave field that the model is unable to produce; these errors are also present in the hindcasts. Despite the limitations, this forecast provides valuable information to bar pilots since it includes the effects of the tidal currents. / Graduation date: 2013

Fluid-structure interaction (FSI) is an interesting and challenging interdisciplinary area comprised of fields such as engineering- fluids/structures/solids, computational science, and mathematics. FSI has several practical engineering applications such as the design of coastal infrastructure (such as bridges, levees) subjected to harsh environments from natural forces such as tsunamis, storm surges, etc. Development of accurate input conditions to more detailed and complex models involving flexible structures in a fluid domain is an important requirement for the solution of such problems. FSI researchers often employ methods that use results from physical wave basin experiments to assess the wave forces on structures. These experiments, while closer to the physical phenomena, often tend to be time-consuming and expensive. Experiments are also not easily accessible for conducting parametric studies. Alternatively, numerical models when developed with similar capabilities will complement the experiments very well because of the lower costs and the ability to study phenomena that are not feasible in the laboratory. This dissertation is aimed at contributing to the solution of a significant component of the FSI problem with respect to engineering applications, covering accurate input to detailed models and a numerical wave basin to complement large-scale laboratory experiments. To this end, this work contains a description of a three-dimensional numerical wave tank (3D-NWT), its enhancements including the piston wavemaker for generation of waves such as solitary, periodic, and focused waves, and validation using large-scale experiments in the 3D wave basin at Oregon State University. Performing simulations involving fluid dynamics is computational-intensive and the complexity is magnified by the presence of the flexible structure(s) in the fluid domain. The models are also required to take care of large-scale domains such as a wave basin in order to be applicable to practical problems. Therefore, undertaking these efforts requires access to high-performance computing (HPC) platforms and development of parallel codes. With these objectives in mind, parallelization of the 3D-NWT is carried out and discussed in this dissertation. / Graduation date: 2011

Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and the Woods Hole Oceanographic Institution), 2007. / Includes bibliographical references. / Surfzone wave height transformation and wave-breaking-driven increases in the mean sea level (setup) are examined on alongshore-uniform beaches with alongshore homogeneous and inhomogeneous wave forcing. While previously derived models predict wave heights adequately (root-mean-square errors typically less than 20%), the models can be improved by tuning a free parameter or by using a new parameterization based on the deep-water wave height. Based on a sensitivity analysis of the cross-shore momentum balance used to predict setup, a one-dimensional (1-D) model is developed that includes wave rollers and bottom stress owing to the mean offshore-directed flow. The model predicts setup accurately at three alongshore homogeneous field sites, as well as at a site where the incident wave field is alongshore non-uniform, suggesting that setup is driven primarily by the cross-shore (1-D) forcing. Furthermore, alongshore gradients of setup can be important to driving alongshore flows in the surfzone, and the 1-D setup model predicts these gradients accurately enough to simulate the observed flows. / by Alex Apotsos. / Ph.D.