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Training ocean engineers for the twenty-first century
Title
Training ocean engineers for the twenty-first century.
Creator
Clark, A. M., Harbor Branch Oceanographic Institute
Date Issued
1992
PURL
http://purl.flvc.org/FCLA/DT/3338512
Subject Headings
Ocean engineering, Ocean engineering--Study and teaching
Format
Document (PDF)
Global distribution of ocean thermal energy conversion (OTEC) resources and applicability in U.S. waters near Florida
Title
Global distribution of ocean thermal energy conversion (OTEC) resources and applicability in U.S. waters near Florida.
Creator
Rauchenstein, Lynn., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The following study explores the worldwide spatial and temporal distributions of electrical power that can be extracted from the ocean's stored solar energy via the process of closed-cycle ocean thermal energy conversion (OTEC). Special emphasis is placed on resources surrounding the state of Florida. The study combines oceanographic input from a state-of-the-art ocean circulation model, the Hybrid Coordinate Ocean Model, with a state-of-the-industry OTEC plant model to predict achievable...
Show moreThe following study explores the worldwide spatial and temporal distributions of electrical power that can be extracted from the ocean's stored solar energy via the process of closed-cycle ocean thermal energy conversion (OTEC). Special emphasis is placed on resources surrounding the state of Florida. The study combines oceanographic input from a state-of-the-art ocean circulation model, the Hybrid Coordinate Ocean Model, with a state-of-the-industry OTEC plant model to predict achievable power values across the world. These power predictions are then constrained by local replenishment rates of cold deep sea water to provide an upper limit to the sustainable OTEC resource. Next, the geographic feasibility of OTEC-coupled and OTEC-independent sea water cooling (air conditioning and refrigeration) are explored. Finally, the model data is validated against in situ oceanic measurements to ensure the quality of the predictions.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3358968
Subject Headings
Ocean energy resources, Ocean engineering, Geothermal energy, Power resources
Format
Document (PDF)
resource assessment of Southeast Florida as related to ocean thermal energy
Title
A resource assessment of Southeast Florida as related to ocean thermal energy.
Creator
Leland, Anna E., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
An assessment of the thermal resource in the Straits of Florida was performed to estimate the Ocean Thermal Energy Conversion (OTEC) potential. Direct measurements of the temperature profile across the Florida Straits were taken from nearshore Southeast Florida to the Exclusive Economic Zone boundary along four evenly spaced transects perpendicular to Florida's Southeast coast, spanning 160 km. Along the southern transects in summer, nearshore cold and warm water resources meet or exceed the...
Show moreAn assessment of the thermal resource in the Straits of Florida was performed to estimate the Ocean Thermal Energy Conversion (OTEC) potential. Direct measurements of the temperature profile across the Florida Straits were taken from nearshore Southeast Florida to the Exclusive Economic Zone boundary along four evenly spaced transects perpendicular to Florida's Southeast coast, spanning 160 km. Along the southern transects in summer, nearshore cold and warm water resources meet or exceed the average 20ÀC temperature difference required for OTEC. In winter, the nearshore average DT of 17.76ÀC can produce 59-75% design net power and 70-86% in spring with DT averaging 18.25ÀC. Offshore along the southern transects, a high steady DT from 18.5- 24ÀC creates an annual average net power of 120-125MW. Along the northern transects, the nearshore resource does not exist, but a consistent OTEC resource is present offshore, providing 70-80% design net power in winter, and 100-158% in spring and summer.
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Date Issued
2009
PURL
http://purl.flvc.org/FAU/369193
Subject Headings
Geothermal energy, Ocean energy resources, Ocean engineering, Power resources
Format
Document (PDF)
INFLUENCE OF SELECTED ADMIXTURES UPON CONCRETE CRACKING DUE TO EMBEDDED METAL CORROSION
Title
INFLUENCE OF SELECTED ADMIXTURES UPON CONCRETE CRACKING DUE TO EMBEDDED METAL CORROSION.
Creator
YAU, SHI-SHEN, Florida Atlantic University
Abstract/Description
The influence of selected iron chelating agents upon corrosion and cracking of steel reinforced concrete has been investigated. Five chelating agents including EDTA, DTPA, TEA, HEDTA and Chel-138 were used. The experiments involved determination of (1) the influence of iron chelating agents on iron solubility limit, (2) the effect of admixtures upon compressive strength of concrete, (3) the influence of chelating admixtures upon steel corrosion and (4) cracking resistance of concrete...
Show moreThe influence of selected iron chelating agents upon corrosion and cracking of steel reinforced concrete has been investigated. Five chelating agents including EDTA, DTPA, TEA, HEDTA and Chel-138 were used. The experiments involved determination of (1) the influence of iron chelating agents on iron solubility limit, (2) the effect of admixtures upon compressive strength of concrete, (3) the influence of chelating admixtures upon steel corrosion and (4) cracking resistance of concrete specimens with and without selected iron chelating agents. Results from test groups (1) and (3) were encouraging; however, compressive strength of concrete specimens with admixtures was less than for specimens with no admixture. In addition, specimens with chelating admixtures had approximately 5.5 to 82 percent shorter cracking time than for the no admixture ones. Explanations for this are presented, and certain conclusions are reached regarding the usefulness of a chelating admixture for mitigating concrete cracking.
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Date Issued
1978
PURL
http://purl.flvc.org/fcla/dt/13952
Subject Headings
Concrete Coatings--Testing, Ocean Engineering
Format
Document (PDF)
SMALL UNMANNED MARINE HYDROKINETIC PLATFORMS FOR POWER GENERATION IN COASTAL AND TIDAL WATERS
Title
SMALL UNMANNED MARINE HYDROKINETIC PLATFORMS FOR POWER GENERATION IN COASTAL AND TIDAL WATERS.
Creator
McKinney, Adriana, Dhanak, Manhar, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description
The feasibility and optimization of small unmanned mobile marine hydrokinetic (MHK) energy platforms for harvesting marine current energy in coastal and tidal waters are examined. A case study of a platform based on the use of a free-surface waterwheel (FSWW) mounted on an autonomous unmanned surface vehicle (USV) was conducted. Such platforms can serve as recharging stations for aerial drones (UAVs), enabling extension of the UAVs’ autonomous operating time. An unmanned MHK platform...
Show moreThe feasibility and optimization of small unmanned mobile marine hydrokinetic (MHK) energy platforms for harvesting marine current energy in coastal and tidal waters are examined. A case study of a platform based on the use of a free-surface waterwheel (FSWW) mounted on an autonomous unmanned surface vehicle (USV) was conducted. Such platforms can serve as recharging stations for aerial drones (UAVs), enabling extension of the UAVs’ autonomous operating time. An unmanned MHK platform potentially meets this need with sustainable power harvested from water currents. For the case study, six different waterwheel configurations were field-tested in the Intracoastal Waterway of South Florida in support of determining the configuration that produced the most power. Required technologies for unmanned operations of the MHK platform were developed and tested. The data from the field-testing were analyzed to develop an empirical relation between the wheel’s theoretical hydrokinetic power produced and the mechanical power harnessed by the MHK platform with various waterwheel configurations during field-testing. The field data was also used to determine the electrical power generated by the FSWW configurations during field-testing. The study has led to the development of standardized testing procedures. The empirical relation is used to examine predicted power production through scaling up different physical aspects of the waterwheel.
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Date Issued
2024
PURL
http://purl.flvc.org/fau/fd/FA00014412
Subject Headings
Ocean engineering, Renewable energy, Marine turbines
Format
Document (PDF)
BACKGROUND STRUCTURE FUNCTIONS, A BASIS TO REDUCE ACOUSTIC POWER REQUIREMENTS AND IMPROVE IMAGES
Title
BACKGROUND STRUCTURE FUNCTIONS, A BASIS TO REDUCE ACOUSTIC POWER REQUIREMENTS AND IMPROVE IMAGES.
Creator
Kobold, Michael C., Beaujean, Pierre-Philippe J., Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
Abstract/Description
Background Structure Functions (BSFs) are wavefront distortion metrics, functions of Sound Speed Profiles (SSPs) that are functions of depth. Use of these BSFs is a synthesis form of Matched Field Processing (MFP) that detects signals that are otherwise lost to receivers. Underwater Acoustics (UWA) can use these models to forecast communication and imaging performance and to reduce power radiated into the sea. This reduction of Transmission Loss (TL) occurs because the commercial wavefront...
Show moreBackground Structure Functions (BSFs) are wavefront distortion metrics, functions of Sound Speed Profiles (SSPs) that are functions of depth. Use of these BSFs is a synthesis form of Matched Field Processing (MFP) that detects signals that are otherwise lost to receivers. Underwater Acoustics (UWA) can use these models to forecast communication and imaging performance and to reduce power radiated into the sea. This reduction of Transmission Loss (TL) occurs because the commercial wavefront control has an input format that accepts BSFs. The BSF plots represent the purely statistical distortion for communications and remote sensing. Another source of TL reduction comes from the enclosed BSF-based phase and phase variance forecasting that protects equalizers from losing phase-lock. Protecting the equalizers protects the Signal To Noise (SNR) ratios. This dissertation derives the UWA version of these metrics and applies them to the following locations of our SSPs: The BSFs use measured, corrected, and verified SSP groups for 132 different locations in the Atlantic Ocean and the Gulf of Mexico from a Navy Ocean Atlas, as well as 64 SSPs in two areas in the littorals, Port Everglades, and Saint Andrew Bay, plus tidal variations. Since BSFs digitize the propagation into one or more segments, our purely statistical phase screen model uses only 3 or 4 degrees of freedom (DOFs) per segment compared to many dozen DOFs for conventional structure functions. The BSFs forecast communications and imaging performance, including range, in locations where acoustic measurements are not available, but SSPs are. A separate algorithm forecasts Gouy phase anomalies from background SSPs, which otherwise requires a priori knowledge of anomaly location and use of Catastrophe theory due to ray theory failure at focuses. Avoiding these anomalies and loss of Phase-Locked Loops (PLLs) also helps maintain SNR and lowers transmission power requirements. Combining with phase parameters and performance forecasts improves UWA propagation efficiency using the background (SSPs). In a spatial version of delay equalization, BSF analysis also produces the enclosed Shear Distortion Ratios (SDRs) for the same locations mentioned above, to allow optimum selection of image enhancement algorithms that mitigate image shear distortion.
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Date Issued
2024
PURL
http://purl.flvc.org/fau/fd/FA00014395
Subject Headings
Underwater acoustics, Sound--Speed, Ocean engineering
Format
Document (PDF)
Determining anchoring systems for marine renewable energy devices moored in a western boundary current
Title
Determining anchoring systems for marine renewable energy devices moored in a western boundary current.
Creator
Seibert, Michael G., Charles E. Schmidt College of Science, Department of Ocean and Mechanical Engineering
Abstract/Description
In this thesis anchoring systems for marine renewable energy devices are examined for an area of interest off the coast of Southeast Florida that contains both ocean current and thermal resources for future energy extraction. Bottom types observed during previous regional benthic surveys are compiled and anchor performance of each potential anchor type for the observed bottom types is compared. A baseline range of environmental conditions is created by combining local current measurements and...
Show moreIn this thesis anchoring systems for marine renewable energy devices are examined for an area of interest off the coast of Southeast Florida that contains both ocean current and thermal resources for future energy extraction. Bottom types observed during previous regional benthic surveys are compiled and anchor performance of each potential anchor type for the observed bottom types is compared. A baseline range of environmental conditions is created by combining local current measurements and offshore industry standards. Numerical simulations of single point moored marine hydrokinetic devices are created and used to extract anchor loading for two potential deployment locations, multiple mooring scopes, and turbine rotor diameters up to 50 m. This anchor loading data is used for preliminary anchor sizing of deadweight and driven plate anchors on both cohesionless and cohesive soils. Finally, the capabilities of drag embedment and pile anchors relevant to marine renewable energy devices are discussed.
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Date Issued
2011
PURL
http://purl.flvc.org/FAU/3172697
Subject Headings
Ocean energy resources, Renewable energy sources, Deep-sea moorings, Ocean engineering, Geothermal energy
Format
Document (PDF)
Solving computer access needs- a local area networkapproach
Title
Solving computer access needs- a local area networkapproach.
Creator
Nall, K. L., Clayton, David L., Harbor Branch Oceanographic Institute
Date Issued
1984
PURL
http://purl.flvc.org/fau/fd/FA00007147
Subject Headings
Local area networks (Computer networks), Ocean engineering, Access (Computer file), Oceanographic research
Format
Document (PDF)
LiOH absorber model testing in underwater life support systems
Title
LiOH absorber model testing in underwater life support systems.
Creator
Wang, Tsen C., Liou, M. C., Hendry, C., Harbor Branch Oceanographic Institute
Date Issued
1988
PURL
http://purl.flvc.org/fau/fd/FA00007496
Subject Headings
Lithium hydroxide, Axial flow, Scrubber (Chemical technology), Carbon dioxide, Ocean engineering, Life Support Systems
Format
Document (PDF)
Computer program for lithium hydroxide - carbon dioxide absorption in underwater life support systems
Title
Computer program for lithium hydroxide - carbon dioxide absorption in underwater life support systems.
Creator
Wang, Tsen C., Liou, M. C., Hendry, C., Harbor Branch Oceanographic Institute
Date Issued
1989
PURL
http://purl.flvc.org/fau/fd/FA00007497
Subject Headings
Lithium hydroxide, Carbon dioxide--Absorption and adsorption, Life Support Systems, Ocean engineering
Format
Document (PDF)
Modeling of axial flow canisters for carbon dioxide-lithium hydroxide absorption in underwater life support systems
Title
Modeling of axial flow canisters for carbon dioxide-lithium hydroxide absorption in underwater life support systems.
Creator
Liou, M. C., Wang, Tsen C., Harbor Branch Oceanographic Institute
Date Issued
1987
PURL
http://purl.flvc.org/fau/fd/FA00007494
Subject Headings
Life Support Systems, Carbon dioxide--Absorption and adsorption, Lithium hydroxide, Axial flow, Ocean engineering
Format
Document (PDF)
Design of hydrodynamic test facility and scaling procedure for ocean current renewable energy devices
Title
Design of hydrodynamic test facility and scaling procedure for ocean current renewable energy devices.
Creator
Valentine, William., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Simulations have been carried out to validate a hydrokinetic energy system non-dimensional scaling procedure. The requirements for a testing facility intended to test such devices will be determined from the results of the simulations. There are 6 simulations containing 3 prototype systems and 2 possible model facility depths to give a range of results. The first 4 tests are conducted using a varying current profile, while the last 2 tests use a constant current profile of 1.6 m/s. The 3...
Show moreSimulations have been carried out to validate a hydrokinetic energy system non-dimensional scaling procedure. The requirements for a testing facility intended to test such devices will be determined from the results of the simulations. There are 6 simulations containing 3 prototype systems and 2 possible model facility depths to give a range of results. The first 4 tests are conducted using a varying current profile, while the last 2 tests use a constant current profile of 1.6 m/s. The 3 prototype systems include a: 6 m spherical buoy, a 12 m spherical buoy and a turbine component system. The mooring line used for the simulations is a 6x19 Wire Rope Wire Core of diameter 100 mm and length 1000 m. The simulations are implemented using Orcaflex to obtain the dynamic behavior of the prototype and scaled system.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3356013
Subject Headings
Ocean energy resources, Research, Renewable energy sources, Sustainable engineering, Materials, Deep-sea moorings
Format
Document (PDF)
fuzzy logic material selection methodology for renewable ocean energy applications
Title
A fuzzy logic material selection methodology for renewable ocean energy applications.
Creator
Welling, Donald Anthony., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The purpose of this thesis is to develop a renewable ocean energy material selection methodology for use in FAU's Ocean Energy Projects. A detailed and comprehensive literature review has been performed concerning all relevant material publications and forms the basis of the developed method. A database of candidate alloys has been organized and is used to perform case study material selections to validate the developed fuzzy logic approach. The ultimate goal of this thesis is to aid in the...
Show moreThe purpose of this thesis is to develop a renewable ocean energy material selection methodology for use in FAU's Ocean Energy Projects. A detailed and comprehensive literature review has been performed concerning all relevant material publications and forms the basis of the developed method. A database of candidate alloys has been organized and is used to perform case study material selections to validate the developed fuzzy logic approach. The ultimate goal of this thesis is to aid in the selection of materials that will ensure the successful performance of renewable ocean energy projects so that clean and renewable energy becomes a reality for all.
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Date Issued
2009
PURL
http://purl.flvc.org/FAU/227980
Subject Headings
Oceanic submersibles, Control systems, Acoustical engineering, Fuzzy algorithms, Renewable energy sources
Format
Document (PDF)
Dynamic analysis of single- and multi-module platforms in waves
Title
Dynamic analysis of single- and multi-module platforms in waves.
Creator
Kling, Kaylie Ann., Florida Atlantic University, Ananthakrishnan, Palaniswamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The response of single- and multi-module floating platforms to surface waves is investigated theoretically. Wave exciting forces are computed using methods based on the Morrison equation and Froude-Krylov hypothesis. The radiation forces are obtained from experimental results of Vugt and where possible diffraction forces using the Haskind reciprocity relation. Heave and pitch response of a one-module platform and hinge-connected two-module platform are determined by integrating the...
Show moreThe response of single- and multi-module floating platforms to surface waves is investigated theoretically. Wave exciting forces are computed using methods based on the Morrison equation and Froude-Krylov hypothesis. The radiation forces are obtained from experimental results of Vugt and where possible diffraction forces using the Haskind reciprocity relation. Heave and pitch response of a one-module platform and hinge-connected two-module platform are determined by integrating the corresponding equations of rigid-body motion. A structural dynamic analysis is also carried out using the Green's function method to determine the elastic flexural response of the platform to waves. The results are compared with the experimental and numerical findings of others. The thesis contributes to a better understanding of rigid-body and elastic response of large ocean platforms subject to wave forces. The methodology is computationally less intensive and therefore can be effectively used for the design of platforms and the validation of numerical algorithms.
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Date Issued
2006
PURL
http://purl.flvc.org/fcla/dt/13399
Subject Headings
Ocean engineering, Wave motion, Theory of, Water waves--Mathematical models, Drilling platforms, Extreme value theory
Format
Document (PDF)
Analysis of ship hull and plate vibrations caused by wave forces
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.
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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)
Dynamics and Control of Autonomous Underwater Vehicles with Internal Actuators
Title
Dynamics and Control of Autonomous Underwater Vehicles with Internal Actuators.
Creator
Li, Bo, Su, Tsung-Chow, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
This dissertation concerns the dynamics and control of an autonomous underwater vehicle (AUV) which uses internal actuators to stabilize its horizontalplane motion. The demand for high-performance AUVs are growing in the field of ocean engineering due to increasing activities in ocean exploration and research. New generations of AUVs are expected to operate in harsh and complex ocean environments. We propose a hybrid design of an underwater vehicle which uses internal actuators instead of...
Show moreThis dissertation concerns the dynamics and control of an autonomous underwater vehicle (AUV) which uses internal actuators to stabilize its horizontalplane motion. The demand for high-performance AUVs are growing in the field of ocean engineering due to increasing activities in ocean exploration and research. New generations of AUVs are expected to operate in harsh and complex ocean environments. We propose a hybrid design of an underwater vehicle which uses internal actuators instead of control surfaces to steer. When operating at low speeds or in relatively strong ocean currents, the performances of control surfaces will degrade. Internal actuators work independent of the relative ows, thus improving the maneuvering performance of the vehicle. We develop the mathematical model which describes the motion of an underwater vehicle in ocean currents from first principles. The equations of motion of a body-fluid dynamical system in an ideal fluid are derived using both Newton-Euler and Lagrangian formulations. The viscous effects of a real fluid are considered separately. We use a REMUS 100 AUV as the research model, and conduct CFD simulations to compute the viscous hydrodynamic coe cients with ANSYS Fluent. The simulation results show that the horizontal-plane motion of the vehicle is inherently unstable. The yaw moment exerted by the relative flow is destabilizing. The open-loop stabilities of the horizontal-plane motion of the vehicle in both ideal and real fluid are analyzed. In particular, the effects of a roll torque and a moving mass on the horizontal-plane motion are studied. The results illustrate that both the position and number of equilibrium points of the dynamical system are prone to the magnitude of the roll torque and the lateral position of the moving mass. We propose the design of using an internal moving mass to stabilize the horizontal-plane motion of the REMUS 100 AUV. A linear quadratic regulator (LQR) is designed to take advantage of both the linear momentum and lateral position of the internal moving mass to stabilize the heading angle of the vehicle. Alternatively, we introduce a tunnel thruster to the design, and use backstepping and Lyapunov redesign techniques to derive a nonlinear feedback control law to achieve autopilot. The coupling e ects between the closed-loop horizontal-plane and vertical-plane motions are also analyzed.
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Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004738, http://purl.flvc.org/fau/fd/FA00004738
Subject Headings
Dynamics., Remote submersibles--Design and construction., Ocean engineering., Fluid dynamics., Nonlinear control theory., Differentiable dynamical systems.
Format
Document (PDF)
Wave Ship Interaction in Transforming Seas
Title
Wave Ship Interaction in Transforming Seas.
Creator
Gong, Fuxian, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
In near-shore transforming seas, as waves approach the shoreline, wave shoaling and sometimes wave breaking take place due to the decreasing water depth. When a ship advances through the transforming seas, the ship body and waves interact with each other substantially and can lead to unknown motions of the ship hull. The physical process of how the wave transforms in the surf zone and how the vehicle actually behaves when it passes through the transforming seas is a complicated issue that...
Show moreIn near-shore transforming seas, as waves approach the shoreline, wave shoaling and sometimes wave breaking take place due to the decreasing water depth. When a ship advances through the transforming seas, the ship body and waves interact with each other substantially and can lead to unknown motions of the ship hull. The physical process of how the wave transforms in the surf zone and how the vehicle actually behaves when it passes through the transforming seas is a complicated issue that triggers considerable research interest. The goal of my research is to characterize the dynamics of a high-speed surface ship model in transforming seas through a parametric numerical study of the shipwave interactions. In this study, the vehicle of interest is a surface effect ship (SES) and we aim to contribute to developing a methodology for simulating the transforming wave environment, including wave breaking, and its interactions with the SES. The thesis work uses a commercial software package ANSYS Fluent to generate numerical waves and model the interface between water and air using the volume of fluid (VoF) method. A ship motion solver and the dynamic mesh are used to enable the modeled ship to perform three degree-of-freedom (DoF) motion and the near-region of the ship hull to deform as well as re-mesh. Non-conformal meshes with hybrid compositions of different cell types and various grid sizes are used in the simulations for different purposes. Five user-defined functions (UDFs) are dynamically linked with the flow solver to incorporates ship/grid motions, wave damping and output of the numerical results. A series of steps were taken sequentially: 1) validation for ship motions including simulation of a static Wigley hull under steady flows to compare against previous experimental results by other researchers, and the comparison between the static SES model under steady flows and the moving SES model advancing in the calm water; 2) study of the ship with 3 DoF advancing in calm water of both constant depth and varying depth; 3) validation for numerical waves, including predictions of numerically progressive waves in both a regular tank and a tank with a sloped fringing reef to compare with theoretical and experimental results, respectively; 4) investigation of the transforming characteristics of the wave traveling over the sloped fringing reef, which mimics the near-shore wave environment and a study of the dynamics of the SES through transforming waves. We find that the flow solver used in this study reliably models the wave profiles along the ship hull. The comparison between a static SES in a current and a moving SES in calm water at the same Froude number shows that although the velocity fields around the vehicle are significantly different, the wave profiles inside and outside the rigid cushion of the vehicle are similar and the resistance force experienced by the vehicle in the two scenarios agree well over time. We conducted five numerical simulations of the vehicle traveling from shallow water to deep water across the transition zone for different Froude numbers. From the results, we find that as the Froude number increases, the wave resistance force on the vehicle becomes larger in both shallow water and deep water. In addition, the overall mean resistance force experienced by the vehicle over the whole trip increases with the Froude number. Statistical analysis of the wave motions suggests that the energy flux decreases dramatically in the onshore direction as the waves break. The more severe the wave-breaking process, the greater the decrease in energy flux. Both the increase of Froude number and the wave steepness apparently increase the resistance force on the vehicle in the shallow water. This thesis work captures the impact of the transforming characteristics of the waves and closely replicates the behavior of how waves interact with a ship in transforming seas through numerical modeling and simulation.
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Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00004916, http://purl.flvc.org/fau/fd/FA00004916
Subject Headings
Hydrodynamics--Mathematical models., Fluid dynamics--Mathematical models., Ocean waves--Measurement., Water waves--Measurement., Coastal engineering.
Format
Document (PDF)
Design and Deployment Analysis of Morphing Ocean Structure
Title
Design and Deployment Analysis of Morphing Ocean Structure.
Creator
Li, Yanjun, Su, Tsung-Chow, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
As humans explore greater depths of Earth’s oceans, there is a growing need for the installation of subsea structures. 71% of the earth’s surface is ocean but there are limitations inherent in current detection instruments for marine applications leading to the need for the development of underwater platforms that allow research of deeper subsea areas. Several underwater platforms including Autonomous Underwater Vehicles (AUVs), Remote Operated Vehicles (ROVs), and wave gliders enable more...
Show moreAs humans explore greater depths of Earth’s oceans, there is a growing need for the installation of subsea structures. 71% of the earth’s surface is ocean but there are limitations inherent in current detection instruments for marine applications leading to the need for the development of underwater platforms that allow research of deeper subsea areas. Several underwater platforms including Autonomous Underwater Vehicles (AUVs), Remote Operated Vehicles (ROVs), and wave gliders enable more efficient deployment of marine structures. Deployable structures are able to be compacted and transported via AUV to their destination then morph into their final form upon arrival. They are a lightweight, compact solution. The wrapped package includes the deployable structure, underwater pump, and other necessary instruments, and the entire package is able to meet the payload capability requirements. Upon inflation, these structures can morph into final shapes that are a hundred times larger than their original volume, which extends the detection range and also provides long-term observation capabilities. This dissertation reviews underwater platforms, underwater acoustics, imaging sensors, and inflatable structure applications then proposes potential applications for the inflatable structures. Based on the proposed applications, a conceptual design of an underwater tubular structure is developed and initial prototypes are built for the study of the mechanics of inflatable tubes. Numerical approaches for the inflation process and bending loading are developed to predict the inflatable tubular behavior during the structure’s morphing process and under different loading conditions. The material properties are defined based on tensile tests. The numerical results are compared with and verified by experimental data. The methods used in this research provide a solution for underwater inflatable structure design and analysis. Several ocean morphing structures are proposed based on the inflatable tube analysis.
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Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004752, http://purl.flvc.org/fau/fd/FA00004752
Subject Headings
Air-supported structures--Design and construction., Remote submersibles--Design and construction., Tensile architecture., Fluid mechanics., Structural dynamics., Ocean engineering., Adaptive control systems.
Format
Document (PDF)