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 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 twodimensional incompressible turbulent flows. The methodology used in the present study is a unilateralstatisticalaverage 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 unilateralstatisticalaverage scheme, compared to Reynolds averaging, is that the firstorder information of the fluctuating velocity...
Show moreA new turbulence model is proposed in this dissertation for twodimensional incompressible turbulent flows. The methodology used in the present study is a unilateralstatisticalaverage 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 unilateralstatisticalaverage scheme, compared to Reynolds averaging, is that the firstorder 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 nonzero quantity, together with a specified length vector, is used to define a 3 x 3 matrix of orthotropic eddy viscosity. In an offstreamline coordinate system, the eddyviscosity 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 boundarylayer flow, turbulent freeshear jet flow, and turbulent wallbounded separation flow without using empirical constants or wallfunctions. Good agreements between the numerical results and experimental data or empirical predictions demonstrate that the unilateralstatisticalaverage scheme and the orthotropic nonlinear eddyviscosity 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.
Show less  Date Issued
 1999
 PURL
 http://purl.flvc.org/fcla/dt/12610
 Subject Headings
 TurbulenceMathematical models, Turbulent boundary layerMathematical 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 seabed and thereby contribute to wave energy dissipation in the bottom boundary layer. Turbulent boundary layers are examined using a highresolution timedependent threedimensional 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 seabed and thereby contribute to wave energy dissipation in the bottom boundary layer. Turbulent boundary layers are examined using a highresolution timedependent threedimensional 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 threedimensional model and onedimensional eddyviscosity based models. Generally, features of the boundary layer are satisfactorily approximated by the eddyviscosity models, with accuracy depending on the wave amplitude, period, phase, and other forcing conditions.
Show less  Date Issued
 2000
 PURL
 http://purl.flvc.org/fcla/dt/12692
 Subject Headings
 WavesMathematical models, Turbulent boundary layerMathematical models
 Format
 Document (PDF)
 Title
 Rapid distortion theory for rotor inflows.
 Creator
 Kawashima, Emilia, Glegg, Stewart A. L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

For aerospace and naval applications where low radiated noise levels are a requirement, rotor noise generated by inflow turbulence is of great interest. Inflow turbulence is stretched and distorted as it is ingested into a thrusting rotor which can have a significant impact on the noise source levels. This thesis studies the distortion of subsonic, high Reynolds number turbulent flow, with viscous effects ignored, that occur when a rotor is embedded in a turbulent boundary layer. The analysis...
Show moreFor aerospace and naval applications where low radiated noise levels are a requirement, rotor noise generated by inflow turbulence is of great interest. Inflow turbulence is stretched and distorted as it is ingested into a thrusting rotor which can have a significant impact on the noise source levels. This thesis studies the distortion of subsonic, high Reynolds number turbulent flow, with viscous effects ignored, that occur when a rotor is embedded in a turbulent boundary layer. The analysis is based on Rapid Distortion Theory (RDT), which describes the linear evolution of turbulent eddies as they are stretched by a mean flow distortion. Providing that the gust does not distort the mean flow streamlines the solution for a mean flow with shear is found to be the same as the solution for a mean potential flow with the addition of a potential flow gust. By investigating the inflow distortion of smallscale turbulence for various simple flows and rotor inflows with weak shear, it is shown that RDT can be applied to incompressible shear flows to determine the flow distortion. It is also shown that RDT can be applied to more complex flows modeled by the Reynolds Averaged Navier Stokes (RANS) equations.
Show less  Date Issued
 2013
 PURL
 http://purl.flvc.org/fau/fd/FA0004030
 Subject Headings
 Computational fluid dynamics, Fluid dynamic measurements, Fluid mechanics  Mathematical models, Turbulence  Computer simulation, Turbulence  Mathematical models
 Format
 Document (PDF)
 Title
 GALLOPING OF AN ELASTICALLY SUPPORTED BLUFF BODY IN TURBULENT FLOW.
 Creator
 Li, Qiang, Florida Atlantic University, Lin, Y. K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

The phenomenon of flowinduced vibration is found in many engineering systems. The fluid flow generates forces on the structure that cause motion of the structure. In turn, the structural motion changes the angle of attack between the flow and the structure, hence the forces on the structure. Furthermore, turbulence generally exists in a natural fluid flow; namely, the fluid velocity contains a random part. Thus, the problem is formulated as a nonlinear system under random excitations. This...
Show moreThe phenomenon of flowinduced vibration is found in many engineering systems. The fluid flow generates forces on the structure that cause motion of the structure. In turn, the structural motion changes the angle of attack between the flow and the structure, hence the forces on the structure. Furthermore, turbulence generally exists in a natural fluid flow; namely, the fluid velocity contains a random part. Thus, the problem is formulated as a nonlinear system under random excitations. This thesis is focused on one type of motion known as galloping. A mathematical model for the motion of an elastically supported square cylinder in turbulent flow is developed. The physical nonlinear equation is converted to ideal stochastic differential equations of the Ito type using the stochastic averaging method. The probability density for the motion amplitude and the values for the most probable amplitudes are obtained for various mean flow velocities and turbulence levels.
Show less  Date Issued
 1987
 PURL
 http://purl.flvc.org/fcla/dt/14361
 Subject Headings
 Random vibrationMathematical models, Turbulence, Fluid dynamics
 Format
 Document (PDF)
 Title
 The acoustic far field of a turbulent boundary layer flow calculated from RANS simulations of the flow.
 Creator
 Blanc, JeanBaptiste., 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 NavierStokes (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 NavierStokes (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
 Subsurface flow generated by a steady wind stress applied at the water surface.
 Creator
 Gurfinkiel, Lionel., Florida Atlantic University, Dhanak, Manhar R.
 Abstract/Description

A turbulent water current induced by winds, through a friction force at the sea surface and subjected to the Coriolis force in shallow water was studied. A Large Eddy Simulation model developed by Zikanov et al. is used to solve the NavierStokes equations. To define the bottom boundary condition, a drag coefficient parameter, based on the ideas of Csanady, is used to evaluate the shear stress at the bottom. To find a suitable bottom boundary condition for this LES simulation, several cases...
Show moreA turbulent water current induced by winds, through a friction force at the sea surface and subjected to the Coriolis force in shallow water was studied. A Large Eddy Simulation model developed by Zikanov et al. is used to solve the NavierStokes equations. To define the bottom boundary condition, a drag coefficient parameter, based on the ideas of Csanady, is used to evaluate the shear stress at the bottom. To find a suitable bottom boundary condition for this LES simulation, several cases were considered with change in drag coefficient property. The effect of variation in the depth of the water column was also considered. Variation in surface deflection of the current, variation of the mass flux and distribution of eddy viscosity with depth of the water column are determined. The cases are compared with the case of a deep water column. Numerical results are also compared with field observations.
Show less  Date Issued
 2003
 PURL
 http://purl.flvc.org/fcla/dt/13030
 Subject Headings
 Oceanatmosphere interactionMathematical models, Turbulence, Wind wavesMathematical models
 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 walkthrough of the entire process utilized to approximate the flow ingested by a Seviktype rotor based on solutions to the Reynolds Averaged NavierStokes equations (RANS). The Multiple Reference Frame fluid model is utilized by the code of ANSYSFLUENT 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 walkthrough of the entire process utilized to approximate the flow ingested by a Seviktype rotor based on solutions to the Reynolds Averaged NavierStokes equations (RANS). The Multiple Reference Frame fluid model is utilized by the code of ANSYSFLUENT 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
 Noise Radiation From A Cylindrical Embossment Immersed In Turbulent Boundary Layer Flow.
 Creator
 Bryan, Benjamin Skyler, Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

This dissertation will consider the sound radiation from forwardfacing steps and a three dimensional cylindrical embossment of very low aspect ratio mounted on a plate. Glegg et al (2014) outlined a theory for predicting the sound radiation from separated flows and applied the method to predicting the sound from forwardfacing steps. In order to validate this theory it has been applied to the results of Catlett et al (2014) and Ji and Wang (2010). This validation study revealed that the...
Show moreThis dissertation will consider the sound radiation from forwardfacing steps and a three dimensional cylindrical embossment of very low aspect ratio mounted on a plate. Glegg et al (2014) outlined a theory for predicting the sound radiation from separated flows and applied the method to predicting the sound from forwardfacing steps. In order to validate this theory it has been applied to the results of Catlett et al (2014) and Ji and Wang (2010). This validation study revealed that the original theory could be adjusted to include a mixed scaling which gives a better prediction. RANS simulations have been performed and used to support the similarities between the forwardfacing step and the cylindrical embossment. The simulations revealed that the cylindrical embossment exhibits a separation zone similar to that of the forwardfacing step. This separation zone has been shown to be the dominant source of noise on the forwardfacing step in previous works and therefore was expected to be the major source of sound from the cylindrical embossment. The sensitivity of this separation zone to the different parameters of the flow has been investigated by performing several simulations with different conditions and geometries. The separation zone was seen to be independent of Reynolds number based on boundary layer thickness but was directly dependent on the height of the cylinder. The theory outlined in Glegg et al (2014) was then reformulated for use with a cylindrical embossment and the predictions have been compared with wind tunnel measurements. The final predictions show good agreement with the wind tunnel measurements and the farfield sound shows a clearly defined directionality that is similar to an axial dipole at low frequencies.
Show less  Date Issued
 2015
 PURL
 http://purl.flvc.org/fau/fd/FA00004484, http://purl.flvc.org/fau/fd/FA00004484
 Subject Headings
 Acoustic models, Aerodynamic noise, Computational fluid dynamcs, Fluid structure interaction, Structural dynamics, Turbulence  Mathematical models
 Format
 Document (PDF)
 Title
 Noise radiation from small steps and cubic roughness elements in turbulent boundary layer flow.
 Creator
 Bryan, Benjamin Skyler, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

Ji and Wang (2010) propose that the dominant source of sound from a forward facing step is the stream wise dipole on the face of the step and that sources acting normal to the flow are negligible. Sound radiation normal to flow of forward facing steps has been measured in wind tunnel experiments previously by Farabee and Casarella (1986, 1991) and Catlett (2010). A method for evaluating sound radiation from surface roughness proposed in Glegg and Devenport (2009) has been adapted and applied...
Show moreJi and Wang (2010) propose that the dominant source of sound from a forward facing step is the stream wise dipole on the face of the step and that sources acting normal to the flow are negligible. Sound radiation normal to flow of forward facing steps has been measured in wind tunnel experiments previously by Farabee and Casarella (1986, 1991) and Catlett (2010). A method for evaluating sound radiation from surface roughness proposed in Glegg and Devenport (2009) has been adapted and applied to flow over a forward facing step which addresses the sound normal to the flow that was previously unaccounted for. Farfield radiation predictions based on this method have been compared with wind tunnel measurements and show good agreement. A second method which evaluates the forcing from a vortex convected past surface roughness using RANS calculations and potential flow information is also evaluated.
Show less  Date Issued
 2012
 PURL
 http://purl.flvc.org/FAU/3358330
 Subject Headings
 Turbulence, Mathematical models, Aerodynamic noise, Fluidstructure interaction, Structural dynamics, Acoustic models, Computational fluid dynamcs
 Format
 Document (PDF)
 Title
 Numerical Assessment of EddyViscosity Turbulence Models of an AxialFlow Turbine at a Low Reynolds Number.
 Creator
 Estrada, Nick Dagoberto, Moslemian, Davood, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

The flow field behavior of axial flow turbines is of great importance, especially in modern designs that may operate at a low Reynolds number. At these low Reynolds numbers, the efficiency loss is significantly augmented compared to higher Reynolds number flows. A detailed incompressible numerical study of a single stage axialflow turbine at a low Reynolds number is investigated with the use of multiple eddyviscosity turbulence models. The study includes epistemic uncertainty quantification...
Show moreThe flow field behavior of axial flow turbines is of great importance, especially in modern designs that may operate at a low Reynolds number. At these low Reynolds numbers, the efficiency loss is significantly augmented compared to higher Reynolds number flows. A detailed incompressible numerical study of a single stage axialflow turbine at a low Reynolds number is investigated with the use of multiple eddyviscosity turbulence models. The study includes epistemic uncertainty quantification as a form of numerical error estimation. The numerical results show good qualitative and quantitative agreement with experimental data. It was found that the shear stress transport (SST) k  Ï‰ turbulence model with rotation/curvature correction and inclusion of transition modeling is most capable at predicting the mean velocity distribution, which is further enhanced when the URANS formulation is employed. However, all the cases indicate a large variation in the prediction of the rootmeansquared of the turbulent velocity fluctuations.
Show less  Date Issued
 2016
 PURL
 http://purl.flvc.org/fau/fd/FA00004587, http://purl.flvc.org/fau/fd/FA00004587
 Subject Headings
 TurbomachinesFluid dynamics., TurbulenceMathematical models., Structural dynamics., Viscous flowMathematical models., Reynolds number., Axial flow.
 Format
 Document (PDF)
 Title
 Predicting the flow & noise of a rotor in a turbulent boundary layer using an actuator disk â€“ Rans approach.
 Creator
 Buono, Armand C., Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

The numerical method presented in this study attempts to predict the mean, nonuniform flow field upstream of a propeller partially immersed in a thick turbulent boundary layer with an actuator disk using CFD based on RANS in ANSYS FLUENT. Three different configurations, involving an infinitely thin actuator disk in the freestream (Configuration 1), an actuator disk near a wall with a turbulent boundary layer (Configuration 2), and an actuator disk with a hub near a wall with a turbulent...
Show moreThe numerical method presented in this study attempts to predict the mean, nonuniform flow field upstream of a propeller partially immersed in a thick turbulent boundary layer with an actuator disk using CFD based on RANS in ANSYS FLUENT. Three different configurations, involving an infinitely thin actuator disk in the freestream (Configuration 1), an actuator disk near a wall with a turbulent boundary layer (Configuration 2), and an actuator disk with a hub near a wall with a turbulent boundary layer (Configuration 3), were analyzed for a variety of advance ratios ranging from J = 0.48 to J =1.44. CFD results are shown to be in agreement with previous works and validated with experimental data of reverse flow occurring within the boundary layer above the flat plate upstream of a rotor in the Virginia Techâ€™s Stability Wind Tunnel facility. Results from Configuration 3 will be used in future aeroacoustic computations.
Show less  Date Issued
 2014
 PURL
 http://purl.flvc.org/fau/fd/FA00004269, http://purl.flvc.org/fau/fd/FA00004269
 Subject Headings
 Aeroelasticity, Computational fluid dynamics, Fluid dynamic measurements, Fluid mechanics  Mathematical models, Turbomachines  Fluid dynamics, Turbulence  Mathematical models
 Format
 Document (PDF)
 Title
 Numerical Simulation of an Ocean Current Turbine Operating in a Wake Field.
 Creator
 Pyakurel, Parakram, VanZwieten, James H., Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

An Ocean Current Turbine (OCT) numerical simulation for creating, testing and tuning flight and power takeoff controllers, as well as for farm layout optimization is presented. This simulation utilizes a novel approach for analytically describing oceanic turbulence. This approach has been integrated into a previously developed turbine simulation that uses unsteady Blade Element Momentum theory. Using this, the dynamical response and power production of a single OCT operating in ambient...
Show moreAn Ocean Current Turbine (OCT) numerical simulation for creating, testing and tuning flight and power takeoff controllers, as well as for farm layout optimization is presented. This simulation utilizes a novel approach for analytically describing oceanic turbulence. This approach has been integrated into a previously developed turbine simulation that uses unsteady Blade Element Momentum theory. Using this, the dynamical response and power production of a single OCT operating in ambient turbulence is quantified. An approach for integrating wake effects into this single device numerical simulation is presented for predicting OCT performance within a farm. To accomplish this, far wake characteristics behind a turbine are numerically described using analytic expressions derived from wind turbine wake models. These expressions are tuned to match OCT wake characteristics calculated from CFD analyses and experimental data. Turbine wake is characterized in terms of increased turbulence intensities and decreased mean wake velocities. These parameters are calculated based on the performance of the upstream OCT and integrated into the environmental models used by downstream OCT. Simulation results are presented that quantify the effects of wakes on downstream turbine performance over a wide range of relative downstream and cross stream locations for both moored and bottom mounted turbine systems. This is done to enable the development and testing of flight and power takeoff controllers designed for maximizing energy production and reduce turbine loadings.
Show less  Date Issued
 2016
 PURL
 http://purl.flvc.org/fau/fd/FA00004737, http://purl.flvc.org/fau/fd/FA00004737
 Subject Headings
 TurbulenceMathematical models., Marine turbinesMathematical models., Wind turbinesAerodynamicsMathematical models., Structural dynamics., Computational fluid dynamics., Fluid dynamic measurements., Atmospheric circulation.
 Format
 Document (PDF)
 Title
 On the Low Order Model of Turbulence in the Wake of a Cylinder and Airfoil â€“ URANS Approach.
 Creator
 Whelchel, Jeremiah Mark, Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

This thesis has described a Reynolds Averaged Navier Stokes approach to modeling turbulence in the wake of a cylinder and airfoil. The mean flow, cross stresses, and twopoint space time correlation structure was analyzed for an untripped cylinder with a Reynolds number based on the cylinder diameter and freestream velocity of 60,000. The same features were also analyzed using this approach for an untripped NACA 0012 airfoil with a Reynolds number based on the airfoil chord and freestream...
Show moreThis thesis has described a Reynolds Averaged Navier Stokes approach to modeling turbulence in the wake of a cylinder and airfoil. The mean flow, cross stresses, and twopoint space time correlation structure was analyzed for an untripped cylinder with a Reynolds number based on the cylinder diameter and freestream velocity of 60,000. The same features were also analyzed using this approach for an untripped NACA 0012 airfoil with a Reynolds number based on the airfoil chord and freestream velocity of 328,000. These simulation results were compared to experimental and newly developed models for validation. The ultimate goal of this present study was to create the twopoint space time correlation function of a cylinder and airfoil wake using RANS calculations which contributes to a larger study where the sound radiated by an open rotor due to ingestion of turbulence.
Show less  Date Issued
 2018
 PURL
 http://purl.flvc.org/fau/fd/FA00013105
 Subject Headings
 TurbulenceNoiseMathematical models., Aerodynamic noise., Wakes (Aerodynamics)., Reynolds number.
 Format
 Document (PDF)
 Title
 FarField Noise From a Rotor in a Wind Tunnel.
 Creator
 Grant, Justin Alexander, Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

This project is intended to demonstrate the current state of knowledge in the prediction of the tonal and broadband noise radiation from a Sevik rotor. The rotor measurements were made at the Virginia Tech Stability Wind Tunnel. Details of the rotor noise and flow measurements were presented by Wisda et al(2014) and Murray et al(2015) respectively. This study presents predictions based on an approach detailed by Glegg et al(2015) for the broadband noise generated by a rotor in an...
Show moreThis project is intended to demonstrate the current state of knowledge in the prediction of the tonal and broadband noise radiation from a Sevik rotor. The rotor measurements were made at the Virginia Tech Stability Wind Tunnel. Details of the rotor noise and flow measurements were presented by Wisda et al(2014) and Murray et al(2015) respectively. This study presents predictions based on an approach detailed by Glegg et al(2015) for the broadband noise generated by a rotor in an inhomogeneous flow, and compares them to measured noise radiated from the rotor at prescribed observer locations. Discrepancies between the measurements and predictions led to comprehensive study of the flow in the wind tunnel and the discovery of a vortex upstream of the rotor at low advance ratios. The study presents results of RANS simulations. The static pressure and velocity profile in the domain near the rotor's tip gap region were compared to measurements obtained from a pressure port array and a PIV visualization of the rotor in the wind tunnel.
Show less  Date Issued
 2015
 PURL
 http://purl.flvc.org/fau/fd/FA00004501, http://purl.flvc.org/fau/fd/FA00004501
 Subject Headings
 Aerodynamic noise, Computational fluid dynamics, Fluid dynamic measurement, Fluid mechanics  Mathematical models, Fluid structure interactioin, Turbomachines  Fluid dynamics, Turbulence  Mathematical models, Unsteady flow (Fluid dynamics)
 Format
 Document (PDF)
 Title
 CFD Study of Pectoral Fins of Larval Zebrafish: Effect of Reynolds Number, Swimming Kinematics and Fin Bending on Fluid Structures and Transport.
 Creator
 Islam, Toukir, Curet, Oscar M., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

Flow Structure and fluid transport via advection around pectoral fin of larval ZebraFish are studied numerically using Immersed Boundary Method, Lagrangian Coherent Structure, passive particle tracing, vortex core evolution and four statistically defined mixing numbers. Experimental fish kinematics for nominal swimming case are obtained from previous researchers and numerically manipulated to analyze the role of different body motion kinematics, Reynolds number and fin morphology on flow...
Show moreFlow Structure and fluid transport via advection around pectoral fin of larval ZebraFish are studied numerically using Immersed Boundary Method, Lagrangian Coherent Structure, passive particle tracing, vortex core evolution and four statistically defined mixing numbers. Experimental fish kinematics for nominal swimming case are obtained from previous researchers and numerically manipulated to analyze the role of different body motion kinematics, Reynolds number and fin morphology on flow structure and transport. Hyperbolic strain field and vortex cores are found to be effective particle transporter and their relative strength are driving force of varying flow structure and fluid transport. Translation and lateral undulation of fish; as a combination or individual entity, has coherent advantages and drawbacks significant enough to alter the nature of fluid advection. Reynolds number increase enhances overall fluid transport and mixing in varying order for different kinematics and nominal bending position of fin has average transport capability of other artificially induced fin morphology.
Show less  Date Issued
 2016
 PURL
 http://purl.flvc.org/fau/fd/FA00004606, http://purl.flvc.org/fau/fd/FA00004606
 Subject Headings
 Reynolds number., Aquatic animals (Physiology), Transport theory., Computational fluid dynamics., Dynamical systems., Continuum physics., TurbulenceMathematical models.
 Format
 Document (PDF)
 Title
 Spectral evaluation of motion compensated adv systems for ocean turbulence measurements.
 Creator
 Egeland, Matthew Nicklas, von Ellenrieder, Karl, VanZwieten, James H., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

A motion compensated ADV system was evaluated to determine its ability to make measurements necessary for characterizing the variability of the ambient current in the Gulf Stream. The impact of IMU error relative to predicted turbulence spectra was quantified, as well as and the ability of the motion compensation approach to remove sensor motion from the ADV measurements. The presented data processing techniques are shown to allow the evaluated ADV to be effectively utilized for quantifying...
Show moreA motion compensated ADV system was evaluated to determine its ability to make measurements necessary for characterizing the variability of the ambient current in the Gulf Stream. The impact of IMU error relative to predicted turbulence spectra was quantified, as well as and the ability of the motion compensation approach to remove sensor motion from the ADV measurements. The presented data processing techniques are shown to allow the evaluated ADV to be effectively utilized for quantifying ambient current fluctuations from 0.02 to 1 Hz (50 to 1 seconds) for dissipation rates as low as 3x107. This measurement range is limited on the low frequency end by IMU error, primarily by the calculated transformation matrix, and on the high end by Doppler noise. Inshore testing has revealed a 0.37 Hz oscillation inherent in the towfish designed and manufactured as part of this project, which can nearly be removed using the IMU.
Show less  Date Issued
 2014
 PURL
 http://purl.flvc.org/fau/fd/FA00004191, http://purl.flvc.org/fau/fd/FA00004191
 Subject Headings
 Fluid dynamic measurements, Fluid mechanics  Mathematical models, Motion control systems, Ocean atmosphere interaction, Ocean circulation, Turbulence, Wave motion, Theory of
 Format
 Document (PDF)