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- Title
- The acoustic far field of a turbulent boundary layer flow calculated from RANS simulations of the flow.
- Creator
- Blanc, Jean-Baptiste., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Boundary layers are regions where turbulence develops easily. In the case where the flow occurs on a surface showing a certain degree of roughness, turbulence eddies will interact with the roughness elements and will produce an acoustic field. This thesis aims at predicting this type of noise with the help of the Computational Fluid Dynamics (CFD) simulation of a wall jet using the Reynolds Average Navier-Stokes (RANS) equations. A frequency spectrum is reconstructed using a representation of...
Show moreBoundary layers are regions where turbulence develops easily. In the case where the flow occurs on a surface showing a certain degree of roughness, turbulence eddies will interact with the roughness elements and will produce an acoustic field. This thesis aims at predicting this type of noise with the help of the Computational Fluid Dynamics (CFD) simulation of a wall jet using the Reynolds Average Navier-Stokes (RANS) equations. A frequency spectrum is reconstructed using a representation of the turbulence with uncorrelated sheets of vorticity. Both aerodynamic and acoustic results are compared to experimental measurements of the flow. The CFD simulation of the flow returns consistent results but would benefit from a refinement of the grid. The surface pressure spectrum presents a slope in the high frequencies close to the experimental spectrum. The far field noise spectrum has a 5dB difference to the experiments.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/368611
- Subject Headings
- Computational fluid dynamics, Turbulence, Mathematical models, Fluid mechanics, Mathematical models, Acoustical engineering
- Format
- Document (PDF)
- Title
- Aerodynamic analysis of a propeller in a turbulent boundary layer flow.
- Creator
- Lachowski, Felipe Ferreira., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Simulating the exact chaotic turbulent flow field about any geometry is a dilemma between accuracy and computational resources, which has been continuously studied for just over a hundred years. This thesis is a complete walk-through of the entire process utilized to approximate the flow ingested by a Sevik-type rotor based on solutions to the Reynolds Averaged Navier-Stokes equations (RANS). The Multiple Reference Frame fluid model is utilized by the code of ANSYS-FLUENT and results are...
Show moreSimulating the exact chaotic turbulent flow field about any geometry is a dilemma between accuracy and computational resources, which has been continuously studied for just over a hundred years. This thesis is a complete walk-through of the entire process utilized to approximate the flow ingested by a Sevik-type rotor based on solutions to the Reynolds Averaged Navier-Stokes equations (RANS). The Multiple Reference Frame fluid model is utilized by the code of ANSYS-FLUENT and results are validated by experimental wake data. Three open rotor configurations are studied including a uniform inflow and the rotor near a plate with and without a thick boundary layer. Furthermore, observations are made to determine the variation in velocity profiles of the ingested turbulent flow due to varying flow conditions.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3360798
- Subject Headings
- Acoustical engineering, Boundary layer control, Multiphase flow, Mathematical models, Fluid mechanics, Mathematical models, Turbulence, Mathematical models, Computatioinal fluid dynamics
- Format
- Document (PDF)
- Title
- Analysis of ship hull and plate vibrations caused by wave forces.
- Creator
- Lakitosh, Fnu, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
In the present dissertation, the hydrodynamic and hydro-elastic characteristics of ship hull and plate vibrations are analyzed using theoretical and numerical methods. The wave forces are determined using a suite of methods which include the Froude-Krylov method for incident wave forces, Wagner's method and ABS rules for the slamming wave force, and numerical methods for nonlinear wave radiation forces. Finite difference methods are developed to determine the wave forced vibrations of ship...
Show moreIn the present dissertation, the hydrodynamic and hydro-elastic characteristics of ship hull and plate vibrations are analyzed using theoretical and numerical methods. The wave forces are determined using a suite of methods which include the Froude-Krylov method for incident wave forces, Wagner's method and ABS rules for the slamming wave force, and numerical methods for nonlinear wave radiation forces. Finite difference methods are developed to determine the wave forced vibrations of ship hull plates which are modeled using a range of plate theories including nonlinear plate theory with and without material damping and orthotropic plate theory for stiffened hull plates. For small amplitude deformation of thin plates, a semi-theoretical superposition method is used to determine the free and forced vibrations. The transient ship hull vibration due to whipping is also analyzed using the finite difference method. Results, in the form of deformations and stress distributions, are obtained for a range of scantling and wave parameters to identify key parameters to consider in ship structural design.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3342196
- Subject Headings
- Vibration (Marine engineering), Hulls (Naval architecture), Ships, Hydraulic impact, Ocean waves, Mathematical models, Fluid dynamics, Mathematical models
- Format
- Document (PDF)
- Title
- Analyzing software repository data to synthesize and visualize relationships between development artifacts.
- Creator
- Mulcahy, James J., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
As computing technology continues to advance, it has become increasingly difficult to find businesses that do not rely, at least in part, upon the collection and analysis of data for the purpose of project management and process improvement. The cost of software tends to increase over time due to its complexity and the cost of employing humans to develop, maintain, and evolve it. To help control the costs, organizations often seek to improve the process by which software systems are developed...
Show moreAs computing technology continues to advance, it has become increasingly difficult to find businesses that do not rely, at least in part, upon the collection and analysis of data for the purpose of project management and process improvement. The cost of software tends to increase over time due to its complexity and the cost of employing humans to develop, maintain, and evolve it. To help control the costs, organizations often seek to improve the process by which software systems are developed and evolved. Improvements can be realized by discovering previously unknown or hidden relationships between the artifacts generated as a result of developing a software system. The objective of the work described in this thesis is to provide a visualization tool that helps managers and engineers better plan for future projects by discovering new knowledge gained by synthesizing and visualizing data mined from software repository records from previous projects.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3333053
- Subject Headings
- Data mining, Mathematical models, Software engineering, Inofrmation visualization, Data processing, Application software, Development, Object-oriented programming (Computer science)
- Format
- Document (PDF)
- Title
- Asymmetric information in fads models in Lâevy markets.
- Creator
- Buckley, Winston S., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Mathematical Sciences
- Abstract/Description
-
Fads models for stocks under asymmetric information in a purely continuous(GBM) market were first studied by P. Guasoni (2006), where optimal portfolios and maximum expected logarithmic utilities, including asymptotic utilities for the informed and uninformed investors, were presented. We generalized this theory to Lâevy markets, where stock prices and the process modeling the fads are allowed to include a jump component, in addition to the usual continuous component. We employ the methods of...
Show moreFads models for stocks under asymmetric information in a purely continuous(GBM) market were first studied by P. Guasoni (2006), where optimal portfolios and maximum expected logarithmic utilities, including asymptotic utilities for the informed and uninformed investors, were presented. We generalized this theory to Lâevy markets, where stock prices and the process modeling the fads are allowed to include a jump component, in addition to the usual continuous component. We employ the methods of stochastic calculus and optimization to obtain analogous results to those obtained in the purely continuous market. We approximate optimal portfolios and utilities using the instantaneous centralized and quasi-centralized moments of the stocks percentage returns. We also link the random portfolios of the investors, under asymmetric information to the purely deterministic optimal portfolio, under symmetric information.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/3337187
- Subject Headings
- Investments, Mathematical models, Capital market, Mathematical models, Finance, Mathematical models, Information theory in economics, Capital asset pricing model, Lâevy processes
- Format
- Document (PDF)
- Title
- Characterizing magnetic noise of AUV for use in towed magnetometer study of internal waves.
- Creator
- Tilley, Dylan., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
As part of a project to study internal waves, FAU plans to utilize an AUV to tow a magnetometer to study electromagnetic signatures from internal waves. This research is focused on the electromagnetic noise issues related to using an AUV to tow the magnetic sensor package. There are active sources of electromagnetic noise caused by an AUV that are present in addition to those induced by the Earth's magnetic field and permanent magnets. To characterize the magnetic noise associated with the...
Show moreAs part of a project to study internal waves, FAU plans to utilize an AUV to tow a magnetometer to study electromagnetic signatures from internal waves. This research is focused on the electromagnetic noise issues related to using an AUV to tow the magnetic sensor package. There are active sources of electromagnetic noise caused by an AUV that are present in addition to those induced by the Earth's magnetic field and permanent magnets. To characterize the magnetic noise associated with the AUV magnetometer tow system, the various active source elements were identified, the orientation sensitivity of the sensors being used was determined, and the magnetic anomaly of a similar AUV which may be eventually be used in a magnetic sensing arrangement was measured. The results are used to show the proposed sensing arrangement will likely not achieve the necessary sensitivity to measure subtle internal wave signals.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3352881
- Subject Headings
- Automatic control, Mathematical models, Electromagnetic measurements, Fluctuations (Physics), Oceanographic submersibles, Underwater acoustics
- Format
- Document (PDF)
- Title
- Collection and analyses of physical data for deep injection wells in Florida.
- Creator
- Gao, Jie., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Deep injection wells (DIW) in Florida are regulated by the U.S. Environmental Protection Agency (USEPA) and the state of Florida through the Underground Injection Control regulations contained within the Safe Drinking Water Act. Underground injection is defined as the injection of hazardous waste, nonhazardous waste, or municipal waste below the lowermost formation containing an underground source of drinking water within one-quarter mile of the wellbore. Municipalities in Florida have been...
Show moreDeep injection wells (DIW) in Florida are regulated by the U.S. Environmental Protection Agency (USEPA) and the state of Florida through the Underground Injection Control regulations contained within the Safe Drinking Water Act. Underground injection is defined as the injection of hazardous waste, nonhazardous waste, or municipal waste below the lowermost formation containing an underground source of drinking water within one-quarter mile of the wellbore. Municipalities in Florida have been using underground injection as an alternative to surface disposal of treated domestic wastewater for nearly 40 years. The research involved collecting data as of September, 2007 on all the Class I DIWs in the state of Florida and evaluating the differences between them. The analysis found regional differences in deep well practice and canonical correlation analyses concluded that depth below the USDW is the most significant factor to prevent upward migration of the injected fluid.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/2796085
- Subject Headings
- Groundwater flow, Mathematical models, Artificial groundwater recharge, Groundwater, Pollution, Management, Deep-well disposal
- Format
- Document (PDF)
- Title
- A comparison of pixel based and object based vegetation community classification in the Arthur R. Marshall Loxahatchee National Wildlife Refuge.
- Creator
- Barone, Dorianne M., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
- Abstract/Description
-
Pixel based and object based vegetation community classification methods were performed using 30 meter spatial resolution Landsat satellite imagery of the Arthur R. Marshall Loxahatchee National Wildlife Refuge (Refuge), a remnant of the northern Everglades. Supervised classification procedures using maximum likelihood and parallelepiped algorithms were used to produce thematic maps with the following vegetation communities : wet prairie, sawgrass, cattail, tree island, brush, aquatic/open...
Show morePixel based and object based vegetation community classification methods were performed using 30 meter spatial resolution Landsat satellite imagery of the Arthur R. Marshall Loxahatchee National Wildlife Refuge (Refuge), a remnant of the northern Everglades. Supervised classification procedures using maximum likelihood and parallelepiped algorithms were used to produce thematic maps with the following vegetation communities : wet prairie, sawgrass, cattail, tree island, brush, aquatic/open water. Spectral data, as well as NDVI, texture and principal component data were used to produce vegetation community classification maps. The accuracy levels of the thematic maps produced were calculated and compared to one another. The pixel based approach using the parallelepiped classification algorithm on the spectral and NDVI dataset had the highest accuracy level. A generalized form of this classification using only three vegetation communities (all wet prairie, tree island/brush and aquatic/open water) was compared to a previously published classification which used 1987 SPOT imagery in order to extract information on possible vegetation community transitions that are occurring within the Refuge. Results of the study indicate that 30 meter spatial resolution may be useful for understanding broad vegetation community trends but not species level trends. Pixel based procedures provide a more accurate classification than object based procedures for this landscape when using 30 meter imagery. Lastly, since 1987 there may be a trend of tree island/brush communities replacing wet prairie communities in the northern part of the Refuge and a transition to wet prairie communities in place of tree island/brush communities in the southern portion of the Refuge.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/FAU/58002
- Subject Headings
- Ecosystem management, Vegetation dynamics, Vegetation classification, Spatial ecology, Mathematical models
- Format
- Document (PDF)
- Title
- Complete thermal design and modeling for the pressure vessel of an ocean turbine -: a numerical simulation and optimization approach.
- Creator
- Kaiser, Khaled., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This thesis is an approach of numerical optimization of thermal design of the ocean turbine developed by the Centre of Ocean Energy and Technology (COET). The technique used here is the integrated method of finite element analysis (FEA) of heat transfer, artificial neural network (ANN) and genetic algorithm (GA) for optimization purposes.
- Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/369194
- Subject Headings
- Thermal analysis, Computer programs, Heat exchangers, Design and construction, Marine turbines, Testing, Mathematical models, Fluid dynamics
- Format
- Document (PDF)
- Title
- Data gateway for prognostic health monitoring of ocean-based power generation.
- Creator
- Gundel, Joseph., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
On August 5, 2010 the U.S. Department of Energy (DOE) has designated the Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) as a national center for ocean energy research and development. Their focus is the research and development of open-ocean current systems and associated infrastructure needed to development and testing prototypes. The generation of power is achieved by using a specialized electric generator with a rotor called a turbine. As with all machines,...
Show moreOn August 5, 2010 the U.S. Department of Energy (DOE) has designated the Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) as a national center for ocean energy research and development. Their focus is the research and development of open-ocean current systems and associated infrastructure needed to development and testing prototypes. The generation of power is achieved by using a specialized electric generator with a rotor called a turbine. As with all machines, the turbines will need maintenance and replacement as they near the end of their lifecycle. This prognostic health monitoring (PHM) requires data to be collected, stored, and analyzed in order to maximize the lifespan, reduce downtime and predict when failure is eminent. This thesis explores the use of a data gateway which will separate high level software with low level hardware including sensors and actuators. The gateway will v standardize and store the data collected from various sensors with different speeds, formats, and interfaces allowing an easy and uniform transition to a database system for analysis.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3342111
- Subject Headings
- Machinery, Monitoring, Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics
- Format
- Document (PDF)
- Title
- Design and analysis of an ocean current turbine performance assessment system.
- Creator
- Young, Matthew T., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This thesis proposes a sensor approach for quantifying the hydrodynamic performance of Ocean Current Turbines (OCT), and investigates the influence of sensor-specific noise and sampling rates on calculated turbine performance. Numerical models of the selected sensors are developed, and then utilized to add stochastic measurement error to numerically-generated, non-stochastic OCT data. Numerically-generated current velocity and turbine performance measurements are used to quantify the relative...
Show moreThis thesis proposes a sensor approach for quantifying the hydrodynamic performance of Ocean Current Turbines (OCT), and investigates the influence of sensor-specific noise and sampling rates on calculated turbine performance. Numerical models of the selected sensors are developed, and then utilized to add stochastic measurement error to numerically-generated, non-stochastic OCT data. Numerically-generated current velocity and turbine performance measurements are used to quantify the relative influence of sensor-specific error and sampling limitations on sensor measurements and calculated OCT performance results. The study shows that the addition of sensor error alters the variance and mean of OCT performance metric data by roughly 7.1% and 0.24%, respectively, for four evaluated operating conditions. It is shown that sensor error results in a mean, maximum and minimum performance metric to Signal to Noise Ration (SNR) of 48.6% and 6.2%, respectively.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3359164
- Subject Headings
- Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics, Stochastic processes, Rotors, Design and construction, Testing
- Format
- Document (PDF)
- Title
- Design and finite element analysis of an ocean current turbine blade.
- Creator
- Asseff, Nicholas S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A composite 3 meter ocean current turbine blade has been designed and analyzed using Blade Element Theory (BET) and commercial Finite Element Modeling (FEM) code, ANSYS. It has been observed that using the numerical BET tool created, power production up to 141 kW is possible from a 3 bladed rotor in an ocean current of 2.5 m/s with the proposed blade design. The blade is of sandwich construction with carbon fiber skin and high density foam core. It also contains two webs made of S2-glass for...
Show moreA composite 3 meter ocean current turbine blade has been designed and analyzed using Blade Element Theory (BET) and commercial Finite Element Modeling (FEM) code, ANSYS. It has been observed that using the numerical BET tool created, power production up to 141 kW is possible from a 3 bladed rotor in an ocean current of 2.5 m/s with the proposed blade design. The blade is of sandwich construction with carbon fiber skin and high density foam core. It also contains two webs made of S2-glass for added shear rigidity. Four design cases were analyzed, involving differences in hydrodynamic shape, material properties, and internal structure. Results from the linear static structural analysis revealed that the best design provides adequate stiffness and strength to produce the proposed power without any structural failure. An Eigenvalue Buckling analysis confirmed that the blade would not fail from buckling prior to overstressed laminate failure if the loading was to exceed the Safety Factor.
Show less - Date Issued
- 2009
- PURL
- http://purl.flvc.org/FAU/221944
- Subject Headings
- Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics, Composite materials, Mathematical models
- Format
- Document (PDF)
- Title
- Detection, localization, and identification of bearings with raceway defect for a dynamometer using high frequency modal analysis of vibration across an array of accelerometers.
- Creator
- Waters, Nicholas., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This thesis describes a method to detect, localize and identify a faulty bearing in a rotating machine using narrow band envelope analysis across an array of accelerometers. This technique is developed as part of the machine monitoring system of an ocean turbine. A rudimentary mathematical model is introduced to provide an understanding of the physics governing the vibrations caused by a bearing with a raceway defect. This method is then used to detect a faulty bearing in two setups : on a...
Show moreThis thesis describes a method to detect, localize and identify a faulty bearing in a rotating machine using narrow band envelope analysis across an array of accelerometers. This technique is developed as part of the machine monitoring system of an ocean turbine. A rudimentary mathematical model is introduced to provide an understanding of the physics governing the vibrations caused by a bearing with a raceway defect. This method is then used to detect a faulty bearing in two setups : on a lathe and in a dynamometer.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3359156
- Subject Headings
- Marine turbines, Mathematical models, Vibration, Measurement, Fluid dynamics, Dynamic testing
- Format
- Document (PDF)
- Title
- Development of an integrated computational tool for design and analysis of composite turbine blades under ocean current loading.
- Creator
- Zhou, Fang., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A computational tool has been developed by integrating National Renewable Energy Laboratory (NREL) codes, Sandia National Laboratories' NuMAD, and ANSYS to investigate a horizontal axis composite ocean current turbine. The study focused on the design, analysis, and life prediction of composite blade considering random ocean current, cyclic rotation, and hurricane-driven ocean current. A structural model for a horizontal axis FAU research OCT blade was developed. Following NREL codes were used...
Show moreA computational tool has been developed by integrating National Renewable Energy Laboratory (NREL) codes, Sandia National Laboratories' NuMAD, and ANSYS to investigate a horizontal axis composite ocean current turbine. The study focused on the design, analysis, and life prediction of composite blade considering random ocean current, cyclic rotation, and hurricane-driven ocean current. A structural model for a horizontal axis FAU research OCT blade was developed. Following NREL codes were used: PreCom, BModes, ModeShape, AeroDyn and FAST. PreComp was used to compute section properties of the OCT blade. BModes and ModeShape calculated the mode shapes of the blade. Hydrodynamic loading on the OCT blade was calculated by modifying the inputs to AeroDyn and FAST. These codes were then used to obtain the dynamic response of the blade, including blade tip displacement, normal force (FN) and tangential force (FT), flap and edge bending moment distribution with respect to blade rotation.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362582
- Subject Headings
- Structural dynamics, Fluid dynamics, Marine turbines, Mathematical models, Turbines, Blades, Design and construction
- Format
- Document (PDF)
- Title
- Development of functional relationships between radar and rain gage data using inductive modeling techniques.
- Creator
- Peters, Delroy., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Traditional methods such as distance weighing, correlation and data driven methods have been used in the estimation of missing precipitation data. Also common is the use of radar (NEXRAD) data to provide better spatial distribution of precipitation as well as infilling missing rain gage data. Conventional regression models are often used to capture highly variant nonlinear spatial and temporal relationships between NEXRAD and rain gage data. This study aims to understand and model the...
Show moreTraditional methods such as distance weighing, correlation and data driven methods have been used in the estimation of missing precipitation data. Also common is the use of radar (NEXRAD) data to provide better spatial distribution of precipitation as well as infilling missing rain gage data. Conventional regression models are often used to capture highly variant nonlinear spatial and temporal relationships between NEXRAD and rain gage data. This study aims to understand and model the relationships between radar (NEXRAD) estimated rainfall data and the data measured by conventional rain gages. The study is also an investigation into the use of emerging computational data modeling (inductive) techniques and mathematical programming formulations to develop new optimal functional approximations. Radar based rainfall data and rain gage data are analyzed to understand the spatio-temporal associations, as well as the effect of changes in the length or availability of data on the models. The upper and lower Kissimmee basins of south Florida form the test-bed to evaluate the proposed and developed approaches and also to check the validity and operational applicability of these functional relationships among NEXRAD and rain gage data for infilling of missing data.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/FAU/166454
- Subject Headings
- Weather control, Mathematical models, Radar meteorology, Technological innovations, Precipitation (Meteorology), Measurement, Weather forecasting, Technological innovations
- Format
- Document (PDF)
- Title
- Differentiating decomposition rates within the ridge-slough microtopography of the central Florida Everglades.
- Creator
- Van der Heiden, Sheryl R., Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
-
The relative rates of detrital decomposition in four vegetation communities within the Everglades' ridge-slough microtopography were evaluated during two trials. Litterbags with community-specific detritus in proportion to each community's composition were put into the four communities; namely, submerged marsh, emergent marsh, short Cladium ridge, and tall Cladium ridge. These litterbags were paired with litterbags containing control leaf litter from Chrysobalanus icaco and Salix caroliniana...
Show moreThe relative rates of detrital decomposition in four vegetation communities within the Everglades' ridge-slough microtopography were evaluated during two trials. Litterbags with community-specific detritus in proportion to each community's composition were put into the four communities; namely, submerged marsh, emergent marsh, short Cladium ridge, and tall Cladium ridge. These litterbags were paired with litterbags containing control leaf litter from Chrysobalanus icaco and Salix caroliniana during the wet and dry season trials, respectively. No regional differences in decomposition were shown, but there were significant differences across communities, attributed to the initial C:N ratio of the detritus, with the fastest decomposition occurring in the deepest submerged marsh followed by emergent marsh, and the shallower ridge communities had equally slower decomposition. Additionally, both controls followed the same pattern. Thus, decomposition contributes to an active self-maintenance mechanism within the vegetation communities which ultimately helps to conserve the ridges and sloughs.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/FAU/166456
- Subject Headings
- Biogeochemistry, Surfaces (Technology), Measurement, Vegatation dynamics, Mathematical models, Wetland ecology
- Format
- Document (PDF)
- Title
- Dissipation and eddy mixing associated with flow past an underwater turbine.
- Creator
- Reza, Zaqie, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The objective of this thesis is to analyze the flow past an ocean current turbine using a finite volume Navier-Stokes CFD solver. A full 3-D RANS approach in a moving reference frame is used to model the flow. By employing periodic boundary conditions, one-third of the flow-field is analyzed and the output is replicated to other sectors. Following validation of the computation with an experimental study, the flow fields and particle paths for the case of uniform and sheared incoming flows...
Show moreThe objective of this thesis is to analyze the flow past an ocean current turbine using a finite volume Navier-Stokes CFD solver. A full 3-D RANS approach in a moving reference frame is used to model the flow. By employing periodic boundary conditions, one-third of the flow-field is analyzed and the output is replicated to other sectors. Following validation of the computation with an experimental study, the flow fields and particle paths for the case of uniform and sheared incoming flows past a generic turbine with various blade pitch angles are evaluated and analyzed. Flow field and wake expansion are visualized. Eddy viscosity effects and its dependence on flow field conditions are investigated.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/2683537
- Subject Headings
- Vibration (Aerodynamics), Fine element method, Marine turbines, Mathematical models, Water currents, Forecasting, Computational fluid dynamics
- Format
- Document (PDF)
- Title
- Effect of median grain size ratio on the compaction behavior of binary granular mixes.
- Creator
- Brenner, Tara Devine., College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Optimization of compaction in granular material without the use of traditional ground improvement methods may be possible by optimizing the percentage of finer material and the median grain size ratio in binary soil mixtures. In this study, the median grain size ratio D50/d50 was explored as a fundamental parpmeter affecting the compaction characteristics of binary mixes made from natural sands as opposed to singular measurements such as fines content and mean grain size traditionally used to...
Show moreOptimization of compaction in granular material without the use of traditional ground improvement methods may be possible by optimizing the percentage of finer material and the median grain size ratio in binary soil mixtures. In this study, the median grain size ratio D50/d50 was explored as a fundamental parpmeter affecting the compaction characteristics of binary mixes made from natural sands as opposed to singular measurements such as fines content and mean grain size traditionally used to represent granular soils. A total of 18 binary granular mixes were synthetically generated from natural sands obtained from Longboat Key, Florida and evaluated through grain size analysis, laboratory compaction and determination of relative density. Results indicate that the D50/d50 ratio shows promise as a fundamental parameter for compaction optimization in binary mixes with values exceeding six approaching the densest packing configuations.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3358329
- Subject Headings
- Granular materials, Dynamic testing, Engineering geology, Soil mechanics, Testing, Micromechanics, Mathematical models
- Format
- Document (PDF)
- Title
- Emission characteristics of a liquid spray sudden expansion combustor using computational fluid dynamics.
- Creator
- Rodriguez, Daniel, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A sudden expansion combustor (SUE) is analyzed using computation fluid dynamics (CFD). CO emissions and NOx emissions are computed for various operating conditions of the SUE combustor using a can type and an annular type geometrical configurations. The goal of this thesis is to see if the SUE combustor is a viable alternative to conventional combustors which utilize swirlers. It is found that for the can type combustor the NOx emissions were quite low compared to other combustor types but...
Show moreA sudden expansion combustor (SUE) is analyzed using computation fluid dynamics (CFD). CO emissions and NOx emissions are computed for various operating conditions of the SUE combustor using a can type and an annular type geometrical configurations. The goal of this thesis is to see if the SUE combustor is a viable alternative to conventional combustors which utilize swirlers. It is found that for the can type combustor the NOx emissions were quite low compared to other combustor types but the CO emissions were fairly high. The annular combustor shows better CO emissions compared to the can type, but the CO emissions are still high compared to other combustors. Emissions can be improved by providing better mixing in the primary combustion zone. The SUE combustor design needs to be further refined in order for it to be a viable alternative to conventional combustors with swirlers.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362574
- Subject Headings
- Fluid dynamics, Data processing, Fluid dynamics, Mathematical models, Computational fluid dynamics, Diffusers, Fluid dynamics
- Format
- Document (PDF)
- Title
- Evaluation of motion compensated ADV measurements for quantifying velocity fluctuations.
- Creator
- Lovenbury, James William., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
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This study assesses the viability of using a towfish mounted ADV for quantifying water velocity fluctuations in the Florida Current relevant to ocean current turbine performance. For this study a motion compensated ADV is operated in a test flume. Water velocity fluctuations are generated by a 1.3 cm pipe suspended in front of the ADV at relative current speeds of 0.9 m/s and 0.15 m/s, giving Reynolds numbers on the order of 1000. ADV pitching motion of +/- 2.5 [degree] at 0.3 Hz and a heave...
Show moreThis study assesses the viability of using a towfish mounted ADV for quantifying water velocity fluctuations in the Florida Current relevant to ocean current turbine performance. For this study a motion compensated ADV is operated in a test flume. Water velocity fluctuations are generated by a 1.3 cm pipe suspended in front of the ADV at relative current speeds of 0.9 m/s and 0.15 m/s, giving Reynolds numbers on the order of 1000. ADV pitching motion of +/- 2.5 [degree] at 0.3 Hz and a heave motion of 0.3 m amplitude at 0.2 Hz are utilized to evaluate the motion compensation approach. The results show correction for motion provides up to an order of magnitude reduction in turbulent kinetic energy at frequencies of motion while the IMU is found to generate 2% error at 1/30 Hz and 9% error at 1/60 Hz in turbulence intensity.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362482
- Subject Headings
- Motion control systems, Fluid dynamic measurements, Fluid mechanics, Mathematical models, Analysis of covariance
- Format
- Document (PDF)