Tidal inlets play a significant role in barrier island sustainability along the barrier islands of southern Louisiana. With increasing tidal prism, major changes are taking place within and adjacent to the inlets. The purpose of this thesis is to examine how Caminada Pass, a tidal inlet along the Caminada-Moreau headland, has evolved through time. Fundamental to this effort is evaluating which processes have contributed toward inlet evolution and what is the response of the inlet-bordering barrier island shorelines of Grand Isle and Elmer’s Island. This effort summarizes previous results and utilizes published bathymetric data, aerial photographs, vector shorelines, satellite images, and seafloor grab samples. The intent of this research is to document the variety of data that are available for future studies of Caminada Pass, an evaluation of long and short-term changes to the system, and an overall better understanding of the inlet dynamics of Caminada Pass.

[pt] Entradas de ar submersas são utilizadas em diversos sistemas de uma aeronave, tais como motor, ar-condicionado, ventilação e turbinas auxiliares. Neste trabalho visa-se estudar, através de simulações numéricas, a influência do uso de um gerador de vórtices sobre a espessura da camada limite a montante de uma entrada de ar submersa, com o intuito de reduzi-la e, assim, aumentar o desempenho deste tipo de entrada. O escoamento em uma entrada NACA convencional é analisado numericamente e seus resultados são tomados como referência para comparações subseqüentes. Em seguida, o gerador de vórtices é projetado e acoplado à entrada NACA convencional. Uma análise paramétrica numérica da influência da posição horizontal, do ângulo de ataque e da área do gerador de vórtices sobre a estrutura do escoamento e sobre os parâmetros de desempenho da entrada de ar é apresentada. Finalmente, um mastro de suporte do gerador de vórtices é projetado e são realizadas simulações do conjunto entrada NACA com gerador de vórtices e mastro para três ângulos de derrapagem do mastro. Os resultados mostram que a presença do gerador de vórtices livre leva a reduções consideráveis da espessura da camada limite e, consequentemente, a ganhos significativos nos parâmetros de desempenho da entrada de ar. Para o caso da entrada NACA com gerador de vórtices livre, os ganhos obtidos em relação à entrada NACA convencional, em termos de eficiência e de vazão mássica, são de até 58% e 21%, respectivamente. No caso da entrada NACA com gerador de vórtices e mastro, o melhor resultado exibe ganhos da ordem de 53%, em termos de eficiência, e de 19%, em termos da vazão mássica que ingressa na entrada de ar. A contribuição do arrasto provocado pela presença do gerador de vórtices com mastro no arrasto total do conjunto entrada NACA com gerador de vórtices e mastro é pequena, menor que 10%. / [en] Submerged air inlets are used for several systems of an aircraft, such as engine, air conditioning, ventilation, and auxiliary turbines. This work intends, through numerical simulations, to study the influence of the use of a vortex generator upon the boundary layer that develops upstream of a submerged air intake, with the aim of decreasing its thickness and, thus, to increase the inlet performance. The flow in a conventional NACA inlet is analyzed numerically and its results are considered as a reference for subsequent comparisons. Then, the vortex generator is designed and assembled to the conventional NACA inlet. A parametric analysis of the influence of the horizontal position, the angle of attack, and the area of the vortex generator on the flow field structure and on the performance parameters of the air inlet is presented. Finally, a support mast of the vortex generator is designed, and simulations are performed for the ensemble NACA inlet with vortex generator and mast for three sideslip angles of the support. The results show that the presence of the vortex generator is responsible for considerable reductions of the boundary layer thickness and, consequently, significant improvements of the performance parameters of the NACA inlet. The improvements, relative to the conventional NACA intake, in terms of ram recovery ratio and mass flow rate, may reach of 58% and 21%, respectively, for the case of the NACA inlet with the freely standing vortex generator. For the case of the NACA inlet with the vortex generator and support, improvements of up to 53%, in terms of ram recovery ratio, and 19%, in terms of mass flow rate ingested by the intake, were obtained. The contribution of the drag induced by the presence of the vortex generator with support on the total drag of the ensemble is smaller than 10%.

John’s Pass is a stable mixed-energy inlet located on a microtidal coast in Pinellas County, Florida. It is hydraulically connected to the northern portion of Boca Ciega Bay. Morphological analysis using a time-series of aerial photographs indicated that anthropogenic activities have influenced the evolution of the tidal deltas and adjacent shorelines at John’s Pass. Previous studies have documented the channel dimensions at the location of the existing bridge and calculated the tidal prism. A chronological analysis of these data yielded an increasing trend in the cross-sectional area at John’s Pass from 1873 to 2001. Anthropogenic activities occurring in Boca Ciega Bay impacting this trend begin in the 1920’s when Indian Pass, approximately 7 km north of John’s Pass, was artificially closed. Other significant events causing an increase or decrease in the crosssectional area at John’s Pass include dredging and filling in the bay, channel dredging at John’s Pass, and jetty construction. More recent data collected from a simultaneous current meter deployment at John’s Pass and Blind Pass were used to calculate the bay area serviced by each inlet resulting in an area serviced by John’s Pass being 1.8x104 km2 and 0.33x104 km2 serviced by Blind Pass. In comparison, Blind Pass captures 14 percent of the tidal prism that John’s Pass captures and John’s Pass captures 87 percent of the bay prism while Blind Pass captures 13 percent. Using the discharge equation and assuming the channel area was largely constant the tidal prism at John’s Pass was 1.07x107 m3 during the twenty-one day deployment. Based on a historical analysis of the tidal prism this study is within 40 percent of the tidal prism calculated by Mehta (1976) and Becker and Ross (2001) and within 20 percent of the tidal prism calculated by Jarrett (1976) and Davis and Gibeaut (1990). An analysis of the current meter time-series indicated that flood velocities in the channel were influenced by a frontal system passing through the study area during the deployment increasing the amount of potential sediment being deposited in the channel thalweg. The maximum ebb and flood-tidal velocities during the deployment were 143 cm/s and 115 cm/s, respectively. Morphological analysis of cross-sectional data from 1995 to 2004 indicated that sediment tends to accumulate along the northern portion of the channel. The channel thalweg tends to accumulate more sediment east of the bridge where wave energy is lower and currents are not as strong. An average net accumulation of 0.5 m per year was estimated along all seven cross-sections. Given the length and width of the surveyed channel, 610 m by approximately 150 m, the sediment flux through the inlet is approximately 45,800 m3 /yr along the channel thalweg. A small amount of sediment accumulation has occurred southwest of the bridge in response to channelized flood flows along the newly constructed jetty. An annual sediment budget was estimated for the John’s Pass inlet system using the beach profiles and inlet bathymetry data between 2000 and 2001. Overall, the inlet system has accumulated more sediment than it has lost during this time period.

We applied culture-independent, next-generation sequencing (NGS) high throughput pyrosequencing, to characterize the microbial communities associated with near shore seawater in Broward County, FL. These waters flow over coral reef communities, which are part of the Florida reef tract, and are close to shore where bathers frequent. Through a close partnership with the NOAA FACE program, 38 total seawater samples were taken from 6 distinct locales -the Port Everglades and Hillsboro Inlets, Hollywood and Broward wastewater outfalls, and the associated reef waters-over the course of one year. Tagged 16S rRNA amplicons were used to generate longitudinal taxonomic profiles of marine bacteria and archaea for one year. 236,322 rRNA quality checked sequences with an average length of 250 base pairs were generated. Sequences were found to vary significantly due to seasonal effects, but depth showed no significant correlation. The most abundant taxa among these samples included Synechococcus, Pelagibacteraceae (SAR11), Bacteroidetes, various Proteobacteria, and Archaea, such as Thermoplasmata. Other taxa found, albeit in low numbers, were the Thiotrichales, and some members of which can indicate pollution, the Alteromonadales, a biofilm forming order. Inlet sequences were found to be significantly different from the outfall and reef communities by various analyses. Unifrac analysis of microbial beta diversity showed a significant clustering pattern for the inlet samples. Precipitation during the three days before and after sampling was low meaning there was little to no high terrestrial runoff during the sampling days. Higher levels of turbidity were seen at the inlet sites and significantly affected the growth of surface colonizing and biofilm forming bacterial families such at the Rhodobacteraceae and Flavobacteriaceae. This study represents one of the first to apply NGS analyses for a deep analysis of microbial community dynamics in these S. Florida waters.

Thesis (Ph.D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, and the Woods Hole Oceanographic Institution), 2001. / Includes bibliographical references. / by Paulo Salles. / Ph.D.

No description available.

Florida's Department of Transportation requires design storm tide hydrographs for coastal waters surrounding tidal inlets along the coast of Florida. These hydrographs are used as open ocean boundary conditions for local bridge scour models. At present, very little information is available on the effect that tidal inlets have on these open coast storm tide hydrographs. Furthermore, current modeling practice enforces a single design hydrograph along the open coast boundary for bridge scour models. This thesis expands on these concepts and provides a more fundamental understanding on both of these modeling areas. A numerical parameter study is undertaken to elucidate the influence of tidal inlets on open coast storm tide hydrographs. Four different inlet-bay configurations are developed based on a statistical analysis of existing tidal inlets along the Florida coast. The length and depth of the inlet are held constant in each configuration, but the widths are modified to include the following four inlet profiles: 1) average Florida inlet width; 2) 100 meter inlet width; 3) 500 meter inlet width; and 4) 1000 meter inlet width. In addition, two unique continental shelf profiles are used to design the ocean bathymetry in the model domains: a bathymetry profile consistent with the west/northeast coast of Florida (wide continental shelf width), and a bathymetry profile similar to the southeast coast of Florida (narrow continental shelf width). The four inlet-bay configurations are paired with each of the bathymetry profiles to arrive at eight model domains employed in this study. Results from these domains are compared to control cases that do not include any inlet-bay system in the computational domain. The ADCIRC-2DDI numerical code is used to obtain water surface elevations for all studies performed herein. The code is driven by astronomic tides at the open ocean boundary, and wind velocities and atmospheric pressure profiles over the surface of the computational domains. Model results clearly indicate that the four inlet-bay configurations do not have a significant impact on the open coast storm tide hydrographs. Furthermore, a spatial variance amongst the storm tide hydrographs is recognized for open coast boundary locations extending seaward from the mouth of the inlet. The results and conclusions presented herein have implications toward future bridge scour modeling efforts. In addition, a hindcast study of Hurricane Ivan in the vicinity of Escambia Bay along the Panhandle of Florida is performed to assess the findings of the numerical parameter study in a real-life scenario. Initially, emphasis is placed on domain scale by comparing model results with historical data for three computational domains: an ocean-based domain, a shelf-based domain, and an inlet-based domain. Results indicate that the ocean-based domain favorably simulates storm surge levels within the bay compared to the other model domains. Furthermore, the main conclusions from the numerical parameter study are verified in the hindcast study: 1) the Pensacola Pass-Escambia Bay system has a minimal effect on the open coast storm tide hydrographs; and 2) the open coast storm tide hydrographs exhibit spatial dependence along typical open coast boundary locations.

abstract: The objective of this study is to understand how to integrate conical spike external compression inlets with high bypass turbofan engines for application on future supersonic airliners. Many performance problems arise when inlets are matched with engines as inlets come with a plethora of limitations and losses that greatly affect an engine’s ability to operate. These limitations and losses include drag due to inlet spillage, bleed ducts, and bypass doors, as well as the maximum and minimum values of mass flow ratio at each Mach number that define when an engine can no longer function. A collection of tools was developed that allow one to calculate the raw propulsion data of an engine, match the propulsion data with an inlet, calculate the aerodynamic data of an aircraft, and combine the propulsion and aerodynamic data to calculate the installed performance of the entire propulsion system. Several trade studies were performed that tested how changing specific design parameters of the engine affected propulsion performance. These engine trade studies proved that high bypass turbofan engines could be developed with external compression inlets and retain effective supersonic performance. Several engines of efficient fuel consumption and differing bypass ratios were developed through the engine trade studies and used with the aerodynamic data of the Concorde to test the aircraft performance of a supersonic airliner using these engines. It was found that none of the engines that were tested came close to matching the supersonic performance that the Concorde could achieve with its own turbojet engines. It is possible to speculate from the results several different reasons why these turbofan engines were unable to function effectively with the Concorde. These speculations show that more tests and trade studies need to be performed in order to determine if high bypass turbofan engines can be developed for effective usage with supersonic airliners in any possible way. / Dissertation/Thesis / Run file and text files from the propulsion simulations performed in NPSS. / Input and output file used in EDET to generate aerodynamic data of Concorde. / Five column propulsion data of tested engines after inlet matching. / Masters Thesis Aerospace Engineering 2018

L'allumage d'ergols injectés dans une chambre de combustion, la propagation du noyau de flamme puis sa stabilisation sont autant de paramètres déterminants pour la conception d'un moteur fusée. Pour ce type d'application, il est nécessaire - du point de vue de la modélisation - de tenir compte du couplage existant entre les effets de compressibilité, les processus de mélange turbulent ainsi que de cinétique chimique, dans un environnement diphasique puisque les ergols sont injectés à l'état liquide. Un modèle Lagrangien a été implanté dans le code de calcul compressible N3S-Natur afin de disposer d'un outil numérique capable de simuler le transitoire d'allumage d'un moteur fusée. La physique représentative de chacun des processus physiques impliqués pendant la phase d'allumage a été incorporée puis validée sur des configurations académiques. Ce travail a permis de mettre en évidence l'importance de la description du mélange à petites échelles pour capturer correctement le développement de la flamme. Il a aussi mis en exergue la nécessité de prendre en compte le transitoire thermique des gouttes d'oxygène liquide afin de reproduire fidèlement sa stabilisation. Enfin, il a nécessité l'extension de la notion de fraction de mélange à des cas pratiques présentant plus de deux entrées afin d'être en mesure de simuler la propagation de l'allumage sur la plaque d'injection. Cette approche basée sur l'introduction d'un injecteur fictif est non seulement utile pour la simulation de l'allumage des moteurs-fusées mais peut aussi être employée dans tout autre système impliquant le mélange entre des courants de réactifs issus de deux entrées ou plus. / In the field of liquid rocket propulsion, ignition, propagation and stabilization of the flame are of first importance for the design of the engine. Computational fluid dynamics (CFD) solvers may provide a great deal of help to proceed with the primary design choice but need to be fed with suited physical models. Important modelling efforts are therefore required to provide reliable computational representations able to take into account compressibility effects, turbulent mixing and chemical kinetics in two-phase flows since ergols are injected at the liquid state. A Lagrangian model has been implemented in the compressible solver N3S-Natur so as to obtain a computational tool able to compute the transient ignition of rocket engines. The physical processes involved at each step of this ignition sequence have been integrated and validated on academically configurations. Three significant contributions rose from this work. First of all, it is highlighted that the description of the micro-mixing is of first importance to correctly capture the flame development. This study also emphasized the need to consider the transient heating of liquid oxygen droplets in order to accurately compute the flame stabilization. Finally, the notion of mixture fraction must be extended to practical devices implying more than two inlets. The proposed approach which is based on the introduction of a fictive injector is not only well suited to rocket engine ignition application but also to deal with other practical devices implying two inlets and more.

A numerical model has been developed for the study of stratified tidal circulation in Indian Arm - a representative inlet on the southern coast of British Columbia. Equations for horizontal velocity, salt conservation, continuity, density (calculated as a linear function of salinity), and the hydrostatic approximation govern the dynamics. All equations have been laterally integrated under the assumption of negligible cross-inlet variability. The model is time dependent and includes nonlinear advective terms, horizontal and vertical turbulent diffusion of salt and momentum, and variations in width and depth. Provisions for surface wind stress and a flux of fresh water are also included, although neither was utilized in this study. An explicit finite difference scheme centred in both time and space was used to solve for the horizontal and vertical velocity components, salinity, and surface elevation on a staggered rectangular grid. A backward Euler scheme was used to suppress the computational mode. Tests using a semi-implicit scheme to solve the finite difference equations over realistic topography led to numerical instabilities at modest values of the time step - in spite of the unconditional stability criteria - suggesting that linear stability analysis may give misleading results for strongly nonlinear systems. Surface elevations calculated from tidal harmonic analysis and salinity timeseries derived from linearly interpolated CTD casts were prescribed at the open boundary. Initial and boundary conditions based on observations in Burrard Inlet and Indian Arm during the winter of 1974-75 were used to study the inlet's response to tidal forcing and to simulate the deep-water renewal that occurred during this period. Coefficients for the horizontal turbulent diffusion of momentum and salt were set equal to 10⁶ cm² s⁻¹. Reducing this value by a factor of two was found to have little impact on the solution. A further reduction to 10³ cm² s⁻¹ led to numerical instabilities under conditions of dense water inflow. The side friction term in the momentum balance was tuned to match calculated and observed dissipation rates in Burrard Inlet; leading to good agreement between the observed and calculated barotropic tide. Contour plots of tidal amplitudes and phases for model currents and salinities revealed a standing wave pattern for the K₁ and M₂ internal tides in Indian Arm; thus allowing for the possibility of resonance. A comparison of model results with vertical amplitude and phase profiles from harmonic analysis of Cyclesonde current meter timeseries at two locations in Indian Arm was consistent with this result. A least-squares fit was made of the vertical modal structure in the model to the complex tidal amplitudes. This led to calculations of the kinetic energy contained in each of the modes along the model inlet for the M₂ and K₁ constituents. Most of the energy was found to be contained in the barotropic and first baroclinic modes, with the latter dominating in the deep basin, and the former dominating near the sill. Second mode energy was significant for the K₁ constituent at some locations in Indian Arm. There are clear indications in the model of barotropic tidal energy being radiated into the inlet basin via the internal tide. Simulations of the influx of dense water into Indian Arm yielded exchange rates that are consistent with observed values and suggest the possibility of fine-tuning the model coefficients to allow prediction of future overturning events. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate