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Title: Effects of external disturbance on the flow development near the boundary of a work table.
Creator: Auche, Edouard Bernard., Florida Atlantic University, Su, Tsung-Chow
Abstract/Description: This thesis addresses the issue of flow development near the boundary of a work table within a clean room. The flow is subjected to periodic external disturbance, either through the pulsation of a source of mass at fixed location, or a moving vortex. The global system consists of a flat table in a parallel oncoming laminar flow. The source of the disturbance is located in the vicinity of the boundary layer. The strength of disturbance is limited in order to apply the quasi-steady boundary...
Show moreThis thesis addresses the issue of flow development near the boundary of a work table within a clean room. The flow is subjected to periodic external disturbance, either through the pulsation of a source of mass at fixed location, or a moving vortex. The global system consists of a flat table in a parallel oncoming laminar flow. The source of the disturbance is located in the vicinity of the boundary layer. The strength of disturbance is limited in order to apply the quasi-steady boundary layer theory. Based on a quasi-steady assumption, a Thwaytes type integration was performed in order to evaluate the displacement thickness and the shear stress on the wall. A parametric study based upon the change of the pulsation, the location and the strength of the disturbance was included in the study. Thwaytes's deviation applied to unsteady cases proved to be successful, and worth being used in further developments.
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/14461
Subject Headings: Boundary layer, Fluid dynamics
Format: Document (PDF)

Title: An Analysis of the Surface Pressure Spectra in a Fluid Flow with a Zero-Pressure Gradient Turbulent Boundary Layer.
Creator: Balestrieri, Frank, Glegg, Stewart, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: The objective of this thesis is to review recently developed empirical and analytical models for the surface pressure and wavenumber spectra for fully developed boundary layers to highlight the effect of assumptions about the turbulence length scales and show how the effects of mean flow Reynolds number has on the spectra shape. The Goody model is used as a reference model to compare the spectra shape as it characterizes the basic physical features of the wall-pressure spectrum under a zero...
Show moreThe objective of this thesis is to review recently developed empirical and analytical models for the surface pressure and wavenumber spectra for fully developed boundary layers to highlight the effect of assumptions about the turbulence length scales and show how the effects of mean flow Reynolds number has on the spectra shape. The Goody model is used as a reference model to compare the spectra shape as it characterizes the basic physical features of the wall-pressure spectrum under a zero-pressure gradient turbulent boundary layer and scales as a function of Reynolds number. The turbulence length scales of the comparison models are modified to observe the effects on the shape of the spectra. A new model is also considered that also scales as a function of Reynolds number and is compared to the Goody model.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013816
Subject Headings: Turbulent boundary layer, Turbulence
Format: Document (PDF)

Title: Aerodynamic analysis of a propeller in a turbulent boundary layer flow.
Creator: Lachowski, Felipe Ferreira., Glegg, Stewart A. L., Graduate College
Date Issued: 2013-04-12
PURL: http://purl.flvc.org/fcla/dt/3361938
Subject Headings: Turbulent boundary layer, Propellers, Aerodynamics
Format: Document (PDF)

Title: Wall Pressure Fluctuation in a Turbulent Channel Flow.
Creator: Denissova, Lyubov, Glegg, Stewart, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: Turbulent flow is a complex three dimensional system of velocity and pressure fluctuations in a fluid that creates vorticity, eddies and other flow structures. In this study we are specifically concerned with the surface pressure fluctuations below a turbulent boundary layer which is one of the primary sources of panel vibration on aircraft fuselages and ship hulls as well a major issue in ship hydrodynamics. The most accepted analytical approaches to describe the surface pressure...
Show moreTurbulent flow is a complex three dimensional system of velocity and pressure fluctuations in a fluid that creates vorticity, eddies and other flow structures. In this study we are specifically concerned with the surface pressure fluctuations below a turbulent boundary layer which is one of the primary sources of panel vibration on aircraft fuselages and ship hulls as well a major issue in ship hydrodynamics. The most accepted analytical approaches to describe the surface pressure fluctuations are the Chase model [1] for the surface pressure wavenumber spectrum and Goody’s model [2] for the pressure spectrum at a point. The most accurate numerical approach to use is Direct Numerical Simulations (DNS) [3]. In this study we compared Chase and Goody’s models against DNS of a turbulent channel flow in the space–time and wavenumber-frequency domains and estimated regions of convergence between the analytical models and the DNS data.
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Date Issued: 2022
PURL: http://purl.flvc.org/fau/fd/FA00014034
Subject Headings: Turbulence, Turbulent boundary layer, Pressure
Format: Document (PDF)

Title: Trailing edge noise propagation through a cascade of blades.
Creator: Roy, Charlie Desire., Florida Atlantic University, Glegg, Stewart A. L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Aircraft engine fan trailing edge noise prediction is very challenging. To achieve a better understanding of the physics of the propagation problem, the fan has been modeled as an infinite cascade of blades and acoustic monopoles and dipoles have been placed at the trailing edges. The flow has been computed using the Transonic Small Disturbance equation. As soon as the critical Mach number is exceeded by the free stream, a supersonic region that joins two consecutive blades appears. It...
Show moreAircraft engine fan trailing edge noise prediction is very challenging. To achieve a better understanding of the physics of the propagation problem, the fan has been modeled as an infinite cascade of blades and acoustic monopoles and dipoles have been placed at the trailing edges. The flow has been computed using the Transonic Small Disturbance equation. As soon as the critical Mach number is exceeded by the free stream, a supersonic region that joins two consecutive blades appears. It completely blocks the sound and limits the study to entirely subsonic flow. In this type of flow, a sound propagation simulator has been implemented. The linearized form of Howe's equation is solved by a high frequency method. The ray caustic problem which causes regular ray tracing failure is fixed by interpolating the field on a preset grid. Results are compared with the analytical solution in uniform flow and computations in realistic flow are presented.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/12990
Subject Headings: Trailing edges (Aerodynamics), Blades, Turbulent boundary layer
Format: Document (PDF)

Title: Turbulence modeling and simulation and related effects on helicopter response with wake dynamics using finite elements and parallelism.
Creator: Dang, Ying Yi., Florida Atlantic University, Gaonkar, Gopal H.
Abstract/Description: Future helicopters will require all-weather capability for stabilized flight through severe atmospheric turbulence. This requirement has brought into focus the effect of turbulence on handling qualities. Accordingly, there is renewed interest in modeling and simulating turbulence and predicting turbulence-induced rotor oscillations. This thesis addresses three fundamental aspects of the problem: (1) modeling and simulation of turbulence including cross-correlation; (2) three-dimensional...
Show moreFuture helicopters will require all-weather capability for stabilized flight through severe atmospheric turbulence. This requirement has brought into focus the effect of turbulence on handling qualities. Accordingly, there is renewed interest in modeling and simulating turbulence and predicting turbulence-induced rotor oscillations. This thesis addresses three fundamental aspects of the problem: (1) modeling and simulation of turbulence including cross-correlation; (2) three-dimensional dynamic-wake effects on rotor response to turbulence and (3) prediction of turbulence and response statistics. The analysis is based on the theory of isotropic and homogeneous turbulence and Taylor's frozen-field approximation. Quasisteady airfoil aerodynamics and a three-dimensional wake are used. Both the isolated blades and isolated rotors are treated. The parallelization is carried out on a massively parallel MasPar SIMD computer. Major conclusions include: (i) The effects of cross-correlation are negligible when two stations lie on the same blade and appreciable when two stations lie on different blades. (ii) In modeling the three-dimensional wake, 3 harmonics are required and dynamic wake has dominant influence on response statistics. (iii) With increasing comprehensiveness of helicopter-turbulence modeling, the sequential execution times increase dramatically; by comparison, the parallel execution times are far lower and, more significantly, remain nearly constant.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15117
Subject Headings: Helicopters, Turbulence, Rotors (Helicopters), Boundary layer noise
Format: Document (PDF)

Title: The Effect of Shear Sheltering on Trailing Edge Noise: A Theoretical Study.
Creator: Jimenez, Ignacio, Glegg, Stewart, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: Shear sheltering is defined as the effect of the mean flow velocity profile in a boundary layer on the turbulence caused by an imposed gust. In aeroacoustic applications turbulent boundary layers interacting with blade trailing edges or roughness elements are an important source of sound, and the effect of shear sheltering on these noise sources has not been studied in detail. Since the surface pressure spectrum below the boundary layer is the primary driver of trailing edge and roughness...
Show moreShear sheltering is defined as the effect of the mean flow velocity profile in a boundary layer on the turbulence caused by an imposed gust. In aeroacoustic applications turbulent boundary layers interacting with blade trailing edges or roughness elements are an important source of sound, and the effect of shear sheltering on these noise sources has not been studied in detail. Since the surface pressure spectrum below the boundary layer is the primary driver of trailing edge and roughness noise, this thesis considers the effect that shear sheltering has on the surface pressure spectrum below a boundary layer. This study presents a model of the incoming turbulence as a vortex sheet at a specified height above the surface and shows, using canonical boundary layers and approximations to numerical results, how the mean flow velocity profile can be manipulated to alter the surface pressure spectrum and hence the associated trailing edge noise. The results from this model demonstrate that different mean velocity profiles drive significant changes in the unsteady characteristics of the flow. The surface pressure fluctuations results also suggest that boundary layers where the shear in the mean velocity profile is significant can be beneficial for the reduction of trailing edge noise at particular frequencies.
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Date Issued: 2020
PURL: http://purl.flvc.org/fau/fd/FA00013535
Subject Headings: Turbulent boundary layer, Trailing edges (Aerodynamics), Aeroacoustics, Boundary layer noise, Shear sheltering
Format: Document (PDF)

Title: A Computational Analysis of Bio-Inspired Modified Boundary Layers for Acoustic Pressure Shielding in A Turbulent Wall Jet.
Creator: Gonzalez, Alexander J., Glegg, Stewart, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Surface pressure fluctuations developed by turbulent flow within a boundary layer is a major cause of flow noise from a body and an issue which reveals itself over a wide range of engineering applications. Modified boundary layers (MBLs) inspired by the down coat of an owl’s wing has shown to reduce the acoustic effects caused by flow noise. This thesis investigates the mechanisms that modified boundary layers can provide for reducing the surface pressure fluctuations in a boundary layer....
Show moreSurface pressure fluctuations developed by turbulent flow within a boundary layer is a major cause of flow noise from a body and an issue which reveals itself over a wide range of engineering applications. Modified boundary layers (MBLs) inspired by the down coat of an owl’s wing has shown to reduce the acoustic effects caused by flow noise. This thesis investigates the mechanisms that modified boundary layers can provide for reducing the surface pressure fluctuations in a boundary layer. This study analyzes various types of MBLs in a wall jet wind tunnel through computational fluid dynamics and numerical surface pressure spectrum predictions. A novel surface pressure fluctuation spectrum model is developed for use in a wall jet boundary layer and demonstrates high accuracy over a range of Reynolds numbers. Non-dimensional parameters which define the MBL’s geometry and flow environment were found to have a key role in optimizing the acoustic performance.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013209
Subject Headings: Turbulent flow, Turbulent boundary layer, Computational fluid dynamics, Wall jets
Format: Document (PDF)

Title: Boundary Layer Control on a Circular Cylindrical Body through Oscillating Lorentz Forcing.
Creator: Seltzer, Ryan K., Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Boundary layer control on a circular cylindrical body through oscillating Lorentz forcing is studied by means of numerical simulation of the vorticity-stream function formulation of the Navier-Stokes equations. The model problem considers axisymmetric seawater flow along an infinite cylinder controlled by an idealized radially directed Lorentz force oscillating spatially and temporally. Under optimum forcing parameters, it is shown that sustainable Lorentz induced vortex rings can travel...
Show moreBoundary layer control on a circular cylindrical body through oscillating Lorentz forcing is studied by means of numerical simulation of the vorticity-stream function formulation of the Navier-Stokes equations. The model problem considers axisymmetric seawater flow along an infinite cylinder controlled by an idealized radially directed Lorentz force oscillating spatially and temporally. Under optimum forcing parameters, it is shown that sustainable Lorentz induced vortex rings can travel along the cylinder at a speed equivalent to the phase speed of forcing . Wall stress is shown to locally change sign in the region adjacent to the vortex, considerably decreasing net viscous drag . Adverse flow behaviors are revealed as a result of studying the effects of the Reynolds numbers, strength of the Lorentz force, and phase speed of forcing for boundary layer control. Adverse flow behaviors inc I ude complex vortex configurations found for suboptimal forcing resulting in a considerable increase in wall stress.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00012549
Subject Headings: Mathematical physics, Lorentz transformations, Boundary layer control, Fluid dynamics
Format: Document (PDF)

Title: Effect of applied periodic strain on coherent structures in a turbulent boundary layer.
Creator: Neravetla, Bharath Reddy, Florida Atlantic University, Dhanak, Manhar R., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The effect of applied periodic straining field on the behavior of coherent vortical structures in the turbulent boundary layer is studied. In particular, the coherent vortical longitudinal structures in the turbulent boundary layer in the form of isolated vortices or in the form of pairs of counter-rotating vortices is considered. The effect on the pressure fluctuations on the wall due to the applied periodic strain is studied. A numerical method using Contour Dynamics technique and...
Show moreThe effect of applied periodic straining field on the behavior of coherent vortical structures in the turbulent boundary layer is studied. In particular, the coherent vortical longitudinal structures in the turbulent boundary layer in the form of isolated vortices or in the form of pairs of counter-rotating vortices is considered. The effect on the pressure fluctuations on the wall due to the applied periodic strain is studied. A numerical method using Contour Dynamics technique and incompressible, inviscid equations of motion is developed to determine the evolution of these structures in time. The pressure fluctuations on the wall are calculated making use of the unsteady Bernoulli's equation. The various parameters associated with the coherent structures in the turbulent boundary layer such as the strength of the vortices, their distance from the wall, separation distance between counter-rotating vortices, the frequency of the applied straining field, the magnitude of the straining field and the stretching rate are varied to study the resultant pressure fluctuations. It is observed that at low applied frequencies, there are high modulations in the surface pressure fluctuations, and at higher applied frequencies of straining field there is reduction in surface pressure fluctuations in the boundary layer.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/15020
Subject Headings: Vortex-motion, Turbulent boundary layer, Pressure--Measurement
Format: Document (PDF)

Title: Hydrodynamics and control of an autonomous underwater vehicle equipped with a vectored thruster.
Creator: Le Page, Yann Georges., Florida Atlantic University, Holappa, Kenneth W., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: In this study, a laminar flow hull shape is implemented on an Autonomous Underwater Vehicle (AUV), with boundary layer suction at the aft end of the hull to prevent separation. The hull shape has the largest diameter of the vehicle near the aft end of the hull resulting in an accelerating flow over the majority of the hull's surface. The problem of axially symmetrical flow around the AUV is solved using a potential flow analysis. A finite difference algorithm evaluates the stream function,...
Show moreIn this study, a laminar flow hull shape is implemented on an Autonomous Underwater Vehicle (AUV), with boundary layer suction at the aft end of the hull to prevent separation. The hull shape has the largest diameter of the vehicle near the aft end of the hull resulting in an accelerating flow over the majority of the hull's surface. The problem of axially symmetrical flow around the AUV is solved using a potential flow analysis. A finite difference algorithm evaluates the stream function, leading to the computation of fluid velocity and pressure fields. The boundary layer characteristics are analyzed to predict the risk of separation. The numerical results are compared with laboratory measurements of the flow using a Particle Image Velocimetry system. Fuzzy Logic Sliding Mode Controllers are implemented to control the vectored thruster vehicle, and are simulated using a six-degree of freedom dynamic model of the vehicle.
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Date Issued: 2000
PURL: http://purl.flvc.org/fcla/dt/15766
Subject Headings: Boundary layer, Laminar flow, Hydrodynamics, Oceanographic submersibles--Mathematical models
Format: Document (PDF)

Title: Numerical simulation of wave energy dissipation in turbulent boundary layers.
Creator: Moneris, Stephanie Sylvie., Florida Atlantic University, Slinn, D. N., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Shoaling surface waves create turbulent shear flows at the sea-bed and thereby contribute to wave energy dissipation in the bottom boundary layer. Turbulent boundary layers are examined using a high-resolution time-dependent three-dimensional numerical model. Simulations estimate the wave energy dissipation in the boundary layer. Results indicate that turbulence levels are coupled to the wave cycle; accelerating flow organizes the boundary layer structure, decelerating flow destabilizes it...
Show moreShoaling surface waves create turbulent shear flows at the sea-bed and thereby contribute to wave energy dissipation in the bottom boundary layer. Turbulent boundary layers are examined using a high-resolution time-dependent three-dimensional numerical model. Simulations estimate the wave energy dissipation in the boundary layer. Results indicate that turbulence levels are coupled to the wave cycle; accelerating flow organizes the boundary layer structure, decelerating flow destabilizes it and flow reversal induces the strongest turbulent bursts. Details of the flow are functions of the Reynolds number, wave frequency, wave complexity, presence of a mean current, and the flow history of the preceding wave period. Mean flow properties are compared between the three-dimensional model and one-dimensional eddy-viscosity based models. Generally, features of the boundary layer are satisfactorily approximated by the eddy-viscosity models, with accuracy depending on the wave amplitude, period, phase, and other forcing conditions.
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Date Issued: 2000
PURL: http://purl.flvc.org/fcla/dt/12692
Subject Headings: Waves--Mathematical models, Turbulent boundary layer--Mathematical models
Format: Document (PDF)

Title: Rational study of incompressible turbulent flows.
Creator: Pu, Xiaoyan., Florida Atlantic University, Yong, Yan, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A new turbulence model is proposed in this dissertation for two-dimensional incompressible turbulent flows. The methodology used in the present study is a unilateral-statistical-average scheme with the concept of orthotropic eddy viscosity. This methodology has never been explored before in any research work of this nature. The distinguished feature of the unilateral-statistical-average scheme, compared to Reynolds averaging, is that the first-order information of the fluctuating velocity...
Show moreA new turbulence model is proposed in this dissertation for two-dimensional incompressible turbulent flows. The methodology used in the present study is a unilateral-statistical-average scheme with the concept of orthotropic eddy viscosity. This methodology has never been explored before in any research work of this nature. The distinguished feature of the unilateral-statistical-average scheme, compared to Reynolds averaging, is that the first-order information of the fluctuating velocity field is retained. This is achieved by dividing the fluctuating velocities into two groups and applying the average only to a single group. It is proved that the mean value of the fluctuating velocities of the first group solutions is not equal to zero. This non-zero quantity, together with a specified length vector, is used to define a 3 x 3 matrix of orthotropic eddy viscosity. In an off-streamline coordinate system, the eddy-viscosity matrix exhibits anisotropy characteristic, where each component of the turbulent stresses is related to all the components of the rate of strains of the mean fluid flow. The present model has been successfully applied to turbulent boundary-layer flow, turbulent free-shear jet flow, and turbulent wall-bounded separation flow without using empirical constants or wall-functions. Good agreements between the numerical results and experimental data or empirical predictions demonstrate that the unilateral-statistical-average scheme and the orthotropic non-linear eddy-viscosity formulation are robust and efficient in modeling basic turbulent flows. Applicability and predictability of the model to more complex engineering turbulence problems are worthy of further investigation in the future research.
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Date Issued: 1999
PURL: http://purl.flvc.org/fcla/dt/12610
Subject Headings: Turbulence--Mathematical models, Turbulent boundary layer--Mathematical models
Format: Document (PDF)

Title: Tearing of an aligned vortex by a current difference in two-layer quasi-geostrophic flow.
Creator: Parthasarathy, Balaji., Florida Atlantic University, Marshall, Jeffrey S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A study of two-layer quasi-geostrophic vortex flow is performed to determine the effect of a current difference between the layers on a vortex initially extending through both the layers. In particular, the conditions under which the current difference can 'tear' the vortex are examined. In the first set of flows studied, the current difference is generated by a (stronger) third vortex in the upper layer located at a large distance from the (weaker) vortex under study. A set of flows are also...
Show moreA study of two-layer quasi-geostrophic vortex flow is performed to determine the effect of a current difference between the layers on a vortex initially extending through both the layers. In particular, the conditions under which the current difference can 'tear' the vortex are examined. In the first set of flows studied, the current difference is generated by a (stronger) third vortex in the upper layer located at a large distance from the (weaker) vortex under study. A set of flows are also considered in which an ambient geostrophic current difference is produced by a non-uniform background potential vorticity field. The results of the study will be useful in determining the conditions under which large geophysical vortex structures, such as cyclones and ocean rings, can extend to large depths even though the mean currents in the ambient flow change significantly along the vortex length.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/14909
Subject Headings: Vortex-motion, Fluid dynamics, Boundary layer control, Flow visualization
Format: Document (PDF)

Title: A model of the horseshoe vortex in juncture flows.
Creator: Monnier, Elie Bertrand., Florida Atlantic University, Dhanak, Manhar R., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: When a boundary-layer flow, either laminar or turbulent, encounters a hemispherical body extending from a surface, a horseshoe-shaped vortex forms at the juncture. In this thesis, we study the evolution of this vortex using a numerical inviscid model and laboratory experiments. The numerical model is based on determining the evolution of the filament using the cut-off method. The assumption is that although the generation of the vortex depends on viscous effects, the dynamic evolution is well...
Show moreWhen a boundary-layer flow, either laminar or turbulent, encounters a hemispherical body extending from a surface, a horseshoe-shaped vortex forms at the juncture. In this thesis, we study the evolution of this vortex using a numerical inviscid model and laboratory experiments. The numerical model is based on determining the evolution of the filament using the cut-off method. The assumption is that although the generation of the vortex depends on viscous effects, the dynamic evolution is well described by inviscid equations of motion. It is found that the vortex filament is fairly steady on the upstream side but on the downstream side, travelling waves appear on it which cannot be suppressed through evolution. For a range of Reynolds number, steady horseshoe-shaped vortex was obtained in the experiments, revealing the shape past the hemisphere. This is compared with the numerical results.
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Date Issued: 1996
PURL: http://purl.flvc.org/fcla/dt/15326
Subject Headings: Boundary layer, Cascades (Fluid dynamics), Flow visualization, Vortex generators
Format: Document (PDF)

Title: Bio-Inspired Modified Turbulent Boundary Layers.
Creator: French, Stone A., Glegg, Stewart, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description: The reduction of drag and sound pressure levels (SPL) are desirable traits in many fluidics’ applications ranging from high-speed transportation to energy generation. Inspiration has been found in some species of owls that possess boundary layer control surface treatments on their wings that appear to reduce SPL while in flight. This modification of the flow over the wings is known as the development of a modified boundary layer (MBL). Virginia Tech is working in collaboration with Florida...
Show moreThe reduction of drag and sound pressure levels (SPL) are desirable traits in many fluidics’ applications ranging from high-speed transportation to energy generation. Inspiration has been found in some species of owls that possess boundary layer control surface treatments on their wings that appear to reduce SPL while in flight. This modification of the flow over the wings is known as the development of a modified boundary layer (MBL). Virginia Tech is working in collaboration with Florida Atlantic University to investigate this reduction in SPL experimentally but requires the assistance of RANS simulation to obtain drag results. This thesis investigates the drag effects of the rod style geometries being evaluated at VT to mimic the MBL of an owl. In doing this it was found that the height of the rods has a direct correlation with the amount of drag induced by the presence of the rods in the flow field.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013826
Subject Headings: Turbulent boundary layer, Sound pressure, Biomimicry, Drag (Aerodynamics)
Format: Document (PDF)

Title: Air-water heat energy fluxes in the lower Florida Keys: Fall and winter months.
Creator: Pitts, Patrick A., Smith, Ned P.
Date Issued: 1995
PURL: http://purl.flvc.org/FCLA/DT/3172859
Subject Headings: Boundary layer (Meteorology), Atmospheric chemistry, Weather, Heat --Transmission, Autumn, Winter, Seasons
Format: Document (PDF)

Title: Wind effect on super-tall buildings using computational fluid dynamics and structural dynamics.
Creator: Assaad, Bilal, Arockiasamy, Madasamy, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
Abstract/Description: Super-tall buildings located in high velocity wind regions are highly vulnerable to large lateral loads. Designing for these structures must be done with great engineering judgment by structural professionals. Present methods of evaluating these loads are typically by the use of American Society of Civil Engineers 7-10 standard, field measurements or scaled wind tunnel models. With the rise of high performance computing nodes, an emerging method based on the numerical approach of...
Show moreSuper-tall buildings located in high velocity wind regions are highly vulnerable to large lateral loads. Designing for these structures must be done with great engineering judgment by structural professionals. Present methods of evaluating these loads are typically by the use of American Society of Civil Engineers 7-10 standard, field measurements or scaled wind tunnel models. With the rise of high performance computing nodes, an emerging method based on the numerical approach of Computational Fluid Dynamics has created an additional layer of analysis and loading prediction alternative to conventional methods. The present document uses turbulence modeling and numerical algorithms by means of Reynolds-averaged Navier-Stokes and Large Eddy Simulation equations applied to a square prismatic prototype structure in which its dynamic properties have also been investigated. With proper modeling of the atmospheric boundary layer flow, these numerical techniques reveal important aerodynamic properties and enhance flow visualization to structural engineers in a virtual environment.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004343, http://purl.flvc.org/fau/fd/FA00004343
Subject Headings: Boundary layer control, Buildings -- Aerodynamics, Computational fluid dynamics, Structural dynamics -- Data processing, Vortex motion
Format: Document (PDF)

Title: Numerical simulations of the wave bottom boundary layer over sand ripples.
Creator: Pierro, Thomas P., Florida Atlantic University, Slinn, D. N., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Surface gravity waves propagating in the nearshore produce an oscillatory freestream potential flow near the seabed and commonly cause regular two-dimensional sand ripples to be formed. The existence of the ripples causes complex turbulent flows to evolve in the boundary layer, which can dissipate significant energy from the surface waves. A time-dependent DNS model is used to solve the Navier-Stokes equations in three dimensions on a transformed curvilinear grid for specified wave parameters...
Show moreSurface gravity waves propagating in the nearshore produce an oscillatory freestream potential flow near the seabed and commonly cause regular two-dimensional sand ripples to be formed. The existence of the ripples causes complex turbulent flows to evolve in the boundary layer, which can dissipate significant energy from the surface waves. A time-dependent DNS model is used to solve the Navier-Stokes equations in three dimensions on a transformed curvilinear grid for specified wave parameters. When compared to smooth beds, simulations over wavy topographies demonstrate that turbulence is enhanced due to flow separation in the lee of the ripple crests. Shear instabilities during phases of weak flow and vortex shedding in times of strong flow work together to sustain turbulence throughout the wave period. Resulting flows over ripples exhibit an increase in boundary layer thickness and dissipation rates, as energy is lost to viscous effects in maintaining turbulence.
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Date Issued: 2001
PURL: http://purl.flvc.org/fcla/dt/12854
Subject Headings: Boundary layer--Mathematical models, Waves--Mathematical models, Sand waves
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.
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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)

FAU Theses and Dissertations (18)	+ -
FAU Graduate Student Research (1)	+ -
HBOI Faculty Contributions (1)	+ -

Turbulent boundary layer (8)	+ -
Boundary layer control (4)	+ -
Turbulence (4)	+ -
Boundary layer (3)	+ -
Fluid dynamics (3)	+ -

Boundary layer noise (2)	+ -
Computational fluid dynamics (2)	+ -
Flow visualization (2)	+ -
Trailing edges (Aerodynamics) (2)	+ -
Turbulent boundary layer--Mathematical models (2)	+ -
Vortex-motion (2)	+ -
Waves--Mathematical models (2)	+ -
Acoustical engineering (1)	+ -
Aeroacoustics (1)	+ -
Aerodynamics (1)	+ -
Atmospheric chemistry (1)	+ -
Autumn (1)	+ -
Biomimicry (1)	+ -
Blades (1)	+ -
Boundary layer (Meteorology) (1)	+ -
Boundary layer--Mathematical models (1)	+ -
Buildings -- Aerodynamics (1)	+ -
Cascades (Fluid dynamics) (1)	+ -
Computatioinal fluid dynamics (1)	+ -
Drag (Aerodynamics) (1)	+ -
Fluid mechanics (1)	+ -
Heat --Transmission (1)	+ -
Helicopters (1)	+ -
Hydrodynamics (1)	+ -
Laminar flow (1)	+ -

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