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Storm-Induced Neashore Sediment Transport
Title
Storm-Induced Neashore Sediment Transport.
Creator
Warren, William F., Briggs, Tiffany Roberts, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
Abstract/Description
Each year storms impact coastal areas, sometimes causing significant morphologic change. Cold fronts are associated with increased wave energy and frequently occur during the winter months along many coasts, such as the Atlantic and Gulf of Mexico. The higher wave energy can be responsible for a large quantity of the sediment transport resulting in rapid morphologic change. Using streamer traps, the vertical distribution of onshore-directed sediment transport during two different cold fronts...
Show moreEach year storms impact coastal areas, sometimes causing significant morphologic change. Cold fronts are associated with increased wave energy and frequently occur during the winter months along many coasts, such as the Atlantic and Gulf of Mexico. The higher wave energy can be responsible for a large quantity of the sediment transport resulting in rapid morphologic change. Using streamer traps, the vertical distribution of onshore-directed sediment transport during two different cold fronts on two low-wave energy beaches (i.e., along the northern Yucatan and southeast Florida) were compared with the resulting morphologic change. The objectives of this study are to: 1) analyze the grain size distribution (statistics) of sediment transported during a cold front, 2) compare the vertical sediment distribution throughout the water column, and 3) compare characteristics of bed sediment to the sediment within the water column. Understanding the changing grain size distribution of bottom sediments in comparison to directional transport (throughout the water column) should help determine the sediment fraction(s) being eroded or deposited, which could greatly improve predictions of storm-induced morphology change.
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Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00004830, http://purl.flvc.org/fau/fd/FA00004830
Subject Headings
Coast changes--Mathematical models., Coastal zone management., Geomorphology., Sediment transport--Analysis., Coastal engineering--Mathematical models.
Format
Document (PDF)
Development and implementation of integrated acoustic and oceanographic numerical modeling in coastal regions
Title
Development and implementation of integrated acoustic and oceanographic numerical modeling in coastal regions.
Creator
Walker, Natasha Maria., Florida Atlantic University, Glegg, Stewart A. L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
An integrated coastal ocean and acoustic propagation model has been implemented to determine the effects of the ocean variations on the acoustic propagation field applied specifically to SFOMC. The ocean dynamics were modeled using the sigma coordinate, orthogonal curvilinear grid, Princeton Ocean Model. By using forcing conditions of tide, river runoff, wind and realistic bottom topography, the resulting time variant regional sound velocity outputs from the model were used as inputs to the...
Show moreAn integrated coastal ocean and acoustic propagation model has been implemented to determine the effects of the ocean variations on the acoustic propagation field applied specifically to SFOMC. The ocean dynamics were modeled using the sigma coordinate, orthogonal curvilinear grid, Princeton Ocean Model. By using forcing conditions of tide, river runoff, wind and realistic bottom topography, the resulting time variant regional sound velocity outputs from the model were used as inputs to the range dependent, parabolic equation, acoustic propagation model, RAM. The results show that the fluctuations in the ocean result in scintillation in the acoustic propagation field, and for higher frequencies this variability is uniformly distributed and at times as much as +/-3 dB. High resolution in the POM grid and the range and depth sizes for RAM were important for obtaining reliable simulation results.
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Date Issued
2002
PURL
http://purl.flvc.org/fcla/dt/12901
Subject Headings
Oceanography--Mathematical models, Underwater acoustics--Mathematical models, Coastal engineering
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)