This dissertation studies the coupled fluid-structure interaction (FSI) of a wave energy converter (WEC) and evaluates the design of a WEC mooring system. The research is conducted in support of conceptual development, field test and performance evaluation of WECs as part of the mission of the Northwest National Marine Renewable...
Students in undergraduate engineering programs typically do not synthesize content learned from disparate course work until the end of their final terms of college. As an example, in undergraduate civil engineering programs, transportation engineering concepts (e.g., geometric alignment, asphalt design procedures) and geotechnical engineering concepts (e.g., shear strength of soils,...
Engineering applications often require fast, accurate solutions of fluid flow around freely moving bodies. The massive parallelism enabled by graphics processing unit (GPU) architecture enables high performance, offering a promising alternative to traditional solver acceleration via multicore central processing units (CPU). However, fully harnessing GPU parallelism requires specialized algorithms and...
Current research on the topic of advanced reactor fuel types include the use of ultrahigh density Uranium-Molybdenum fuels, towards their use in high-performance research reactors. These reactors operate with high power densities, and the increased cooling requirements therefore place high relevance on the fluid-structure interaction with these fuel elements; therefore...
The fluid impact forces on a bridge superstructure in horizontal and vertical directions due to tsunamis represented by solitary waves are investigated through a large-scale laboratory experiment and numerical simulations. The experiment is conducted in a two-dimensional wave basin using a 1:5 scaled reinforced concrete bridge deck model tested under...
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Nomenclature
𝐴𝐺𝑎𝑝 Area between each girder
𝐴𝑓 Area of the bottom of the structure or
The finite element software framework, OpenSees, has been used by researchers
to simulate the response of structural and geotechnical systems to earthquake loading. Implementation of the Particle Finite Element Method (PFEM) has made it possible to simulate hydrodynamic forces through fluid-structure interaction (FSI) in OpenSees. To validate the FSI implementation...
This study presents a methodology for power take off (PTO) forecasting for an array of heave wave energy converters (WECs). Based on spectral data obtained directly from the National Data Buoy Center, representative realistic sea states are generated at the location of the WECs, and by using two wave-structure interaction...
The understanding and prediction how coastal wetland vegetation attenuates wave action has received renewed attention with global climate change impacts and increasing populations on coastlines. Conventional attenuation models utilize empirical drag coefficients, but these coefficients exhibit a wide range of values, and there is some uncertainty in the relative importance...
Cells represent microcosms of spatial and temporal structural organization, with the achievement of internal spatial organization relying upon a collection of macromolecular motor complexes to transport and localize components throughout the cell. Cytoplasmic dynein is one such motor complex, and is the principal ATP-dependent motor for retrograde transport along microtubules...
Mechanical vibrations compromise the integrity of key components of thermal power plants. Without careful design, strong resonances during steady state operation can wear these components to the point of failure, leading to an unsafe situation that may force a plant to shut down. The purpose of this research is to...
Recent tsunami field surveys from the 2011 Great East Japan Earthquake and Tsunami have recorded numerous examples of tsunami-induced soil instability: significant scour around foundations, foundation failure of piles, and other damage caused by liquefaction. From the observations of soil instability leading to the failure of critical coastal structures, it...
As computational power increases, so does the desire to use fluid-structure interaction (FSI) software to design complex systems and components such as fuel plates. Presently, an effort is underway to support the design and qualification of a new nuclear fuel material which is intended for applications in select, plate-type, research...
Fluid-structure interaction (FSI) is a very interesting and challenging multi-disciplinary field involving interaction of a movable or deformable structure with an internal or surrounding fluid flow. FSI has several practical engineering applications such as the determination of the hydrodynamic forces on a structure or the dynamics of motion of bodies...
To facilitate the evaluation and design of structures subjected to fluid loading, a study of fluid-structure interaction (FSI) using the particle finite element method (PFEM) is presented to approximate the responses and sensitivities of structures which interact with fluid. A wide range of structural types are permissible by making no...
During the 2011 Great East Japan Earthquake and Tsunami, numerous bridge structures were damage or destroyed. The damage to bridge systems was caused by long duration strong ground shaking, tsunami inundation forces, or both. Long duration strong ground shaking from subduction zone earthquakes and the multi-hazard scenario of combined earthquake...
Wave energy holds great promise to be part of the alternative energy portfolio that will provide independence from fossil fuels. As wave energy converter (WEC) technologies mature, designing effective control strategies to extract maximum energy, extend device life, coordinate WEC operation within an array, or mitigate negative impacts of a...
Earthquake engineering analyses are often performed using shallow, crustal earthquake motions (e.g., 1940 El Centro). However, large areas of the world are subject to subduction zone earthquake motions (e.g., the Pacific Northwest). A subduction zone earthquake motion is characterized by its long duration (e.g., strong shaking lasts for more than...
Since 2004 there have been multiple devastating tsunamis around the globe triggered by large magnitude earthquakes; with the most recent being the Tohoku, Japan tsunami in March 2011. These tsunamis have caused significant loss of life and damage to the coastal communities impacted by these powerful waves. The resulting devastation...
This thesis investigates the applicability of the finite element method to model wave energy converter (WEC) hydroelasticity using LS-DYNA. The proposed methodology uses the Arbitrary Lagrangian-Eulerian formulation to model Fluid-Structure Interaction (FSI) between the WEC and the fluid elements. This formulation allows for time-domain modeling of higher order effects such...
Fluid-structure interaction (FSI) is an interesting and challenging interdisciplinary area comprised of fields such as engineering- fluids/structures/solids, computational science, and mathematics. FSI has several practical engineering applications such as the design of coastal infrastructure (such as bridges, levees) subjected to harsh environments from natural forces such as tsunamis, storm surges,...
Recently, the concept of performance based design has become popular for many types of structures, including port facilities under seismic loading. For the case of pile-supported wharves, the level of performance is generally estimated using the displacement capacity of the structure. Therefore, understanding soil-pile interaction is one of the most...
The goal of this study was to develop an understanding of the nature of surge wave loading on
wood framed residential structures for a variety of building configurations and test conditions.
The objectives of the study were: (1) to measure forces on a 1/6th scale wood framed
residential structure, (2)...
Complex oscillations including chaotic motions have been identified in off-shore and submerged mooring systems characterized by nonlinear fluid-structure interactions and restoring forces. In this paper, a means of controlling these nonlinear oscillations is addressed. When applied, the controller is able to drive the system to periodic oscillations of arbitrary periodicity....
Commonly proposed ocean wave energy converters (OWEC) use inefficient and maintenance demanding intermediate hydraulic and pneumatic systems. We propose a novel rotary direct-drive OWEC that eliminates these intermediate stages. The new device employs a contactless force transmission system (CFTS) comprising a “piston” and a “cylinder” and a ball screw to...
A numerical model for the simulation of fully-coupled fluid-structure
interaction is developed in this study. In modeling the fluid, the Reynolds
Averaged Navier-Stokes equations are solved for an incompressible viscous
fluid field and a k-ε model is employed for turbulence computations.
Hydrodynamic forces obtained by the integration of the fluid...
As part of a research program to study the transitional region of N=88
isotones, ¹⁵²Tb was produced by the reaction ¹⁵¹Eu(α,3n)¹⁵²Tb in the 88" cyclotron
located at LBNL. Gamma-ray spectroscopy of the radiation emitted from excited
¹⁵²Gd following the β⁺ decay of ¹⁵²Tb has been performed using an array of...
This dissertation presents the results of a research effort conducted to better understand the seismic performance and analysis of pile-supported wharves. Given the limited number of well-documented field case histories, the seismic performance of pile-supported wharves has been poorly quantified, and the analysis methods commonly employed in engineering practice have...
The characteristics of the free surface in an orifice driven by a periodic forcing function have been studied both theoretically and experimentally. In the theoretical study, two wall boundary condition cases were examined: 1) the radial velocity at the wall of the orifice is zero; and 2) the axial velocity...