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Control Surfaces Of Aquatic Vertebrates: Active And Passive Design And Function, Frank E. Fish, George V. Lauder

Biology Faculty Publications

Aquatic vertebrates display a variety of control surfaces that are used for propulsion, stabilization, trim and maneuvering. Control surfaces include paired and median fins in fishes, and flippers and flukes in secondarily aquatic tetrapods. These structures initially evolved from embryonic fin folds in fishes and have been modified into complex control surfaces in derived aquatic tetrapods. Control surfaces function both actively and passively to produce torque about the center of mass by the generation of either lift or drag, or both, and thus produce vector forces to effect rectilinear locomotion, trim control and maneuvers. In addition to fins and flippers, …

Reach-Scale River Metabolism Across Contrasting Sub-Catchment Geologies: Effect Of Light And Hydrology, Lorenzo Rovelli, Karl M. Attard, Andrew Binley, Catherine M. Heppell, Henrik Stahl, Mark Trimmer, Ronnie N. Glud

All Works

© 2017 The Authors Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography We investigated the seasonal dynamics of in-stream metabolism at the reach scale (∼ 150 m) of headwaters across contrasting geological sub-catchments: clay, Greensand, and Chalk of the upper River Avon (UK). Benthic metabolic activity was quantified by aquatic eddy co-variance while water column activity was assessed by bottle incubations. Seasonal dynamics across reaches were specific for the three types of geologies. During the spring, all reaches were net autotrophic, with rates of up to 290 mmol C …

Screening And Plasma Oscillations In An Electron Gas In The Hydrodynamic Approximation, Eugene B. Kolomeisky, Joseph P. Straley

Physics and Astronomy Faculty Publications

A hydrodynamic theory of screening in a generic electron gas of arbitrary dimensionality is given that encompasses all previously studied cases and clarifies the predictions of the many-body approach. We find that long-wavelength plasma oscillations are classical phenomena with quantum-mechanical effects playing no explicit role. The character of the oscillations is solely dictated by the dimensionality of the electron system and its equation of state in the neutral limit. Materials whose excitations are described by the Dirac dispersion law—such as doped graphene or a Weyl semimetal—are no exception to this rule.

Applications Of Cfd Simulations On Chemical Processing Equipment Designs, Gongqiang He

LSU Doctoral Dissertations

The objective of this work is to achieve process intensification by seeking optimal equipment design with CFD investigations. In this work, two projects on chemical equipment design have been discussed.

The first project is on design and optimization of fractal distributor in a novel ion-exchanger. Flow distributors are adopted extensively by chemical industry to distribute an incoming process stream uniformly to the downstream equipment. Currently, the performance of chemical equipment installed with conventional distributor is severely undermined due to poor flow distribution. For conventional distributors such as spray nozzle distributors, their design concept is based on maintaining very high pressure …

The Formation And Dynamics Of Clouds In The Environment Of Active Galactic Nuclei, Timothy Waters

UNLV Theses, Dissertations, Professional Papers, and Capstones

Active galactic nuclei (AGN) are among the most luminous objects in the universe and are known to be powered by accretion onto supermassive black holes in the centers of galaxies. AGN clouds are prominent components of successful models that attempt to unify the diversity of AGN. These clouds are often hypothesized to be the source of the broad and narrow line emission features seen in AGN spectra. Moreover, the high column densities of gas needed to account for broad absorption lines has been attributed to the same population of clouds, while the motion of AGN clouds has been invoked to …

In Between Forces, Jungyun Lee

Masters Theses

In order to live, humans make buildings in nature and live in there. This fact has not changed since the birth of mankind. It means to live in a certain space, because a medium of building is necessary for man to survive safely in nature. Based on these mediators mankind has been living. In addition, villages and cities were created and continued to grow in size. As a result, the building, which is the mediator, has been different in shape and size. In an expanding city, are city and nature now balanced? How do we balance it? How can we …

Predicting The Impacts Of Mississippi River Diversions And Sea-Level Rise On Spatial Patterns Of Eastern Oyster Growth Rate And Production, Hongqing Wang, Qin Chen, Megan K. La Peyre, Kelin Hu, Jerome F. La Peyre

Faculty Publications

© 2017 There remains much debate regarding the perceived tradeoffs of using freshwater and sediment diversions for coastal restoration in terms of balancing the need for wetland restoration versus preserving eastern oyster (Crassostrea virginica) production. Further complicating the issue, climate change-induced sea-level rise (SLR) and land subsidence are also expected to affect estuarine water quality. In this study, we developed a process-based numerical modeling system that couples hydrodynamic, water quality, and oyster population dynamics. We selected Breton Sound Estuary (BSE) (∼2740 km2) in the eastern Mississippi River Deltaic Plain since it is home to several of the largest public oyster …

Motion Dynamics Of Dropped Cylindrical Objects, Gong Xiang

University of New Orleans Theses and Dissertations

Dropped objects are among the top ten causes of fatalities and serious injuries in the oil and gas industry. Objects may be dropped during lifting or any other offshore operation. Concerns of health, safety, and the environment (HSE) as well as possible damages to structures require the prediction of where and how a dropped object moves underwater. This study of dropped objects is subdivided into three parts. In the first part, the experimental and simulated results published by Aanesland (1987) have been successfully reproduced and validated based on a two-dimensional (2D) theory for a dropped drilling pipe model. A new …

An Experimental Study In The Hydroelastic Response Of An Aluminum Wedge In Drop Tests, Jonathan R. Eastridge

University of New Orleans Theses and Dissertations

Slamming of marine planing craft is expected to arise due to the high speed nature of their operating conditions. High hydrodynamic forces are inevitably induced causing the shell plating to deflect, which in turn can influence the flow physics surrounding the hull. In order to study the hull’s hydroelastic response due to a slamming event, wedge drop experiments were performed with an aluminum wedge of 57 inches in length, 47 inches in breadth, and 20 degree deadrise with 1/4 in. thick unstiffened bottom panels. The elastic behavior of the hull plating was measured via two methods. The first method uses …

Spectre: A Task-Based Discontinuous Galerkin Code For Relativistic Astrophysics, Lawrence E. Kidder, Scott E. Field, Francois Foucart, Erik Schnetter, Saul A. Teukolsky, Andy Bohn, Nils Deppe, Peter Diener, François Hébert, Jonas Lippuner, Jonah Miller, Christian D. Ott, Mark A. Scheel, Trevor Vincent

Faculty Publications

We introduce a new relativistic astrophysics code, SpECTRE, that combines a discontinuous Galerkin method with a task-based parallelism model. SpECTRE's goal is to achieve more accurate solutions for challenging relativistic astrophysics problems such as core-collapse supernovae and binary neutron star mergers. The robustness of the discontinuous Galerkin method allows for the use of high-resolution shock capturing methods in regions where (relativistic) shocks are found, while exploiting high-order accuracy in smooth regions. A task-based parallelism model allows efficient use of the largest supercomputers for problems with a heterogeneous workload over disparate spatial and temporal scales. We argue that the locality and …

Hydraulics Near Unscreened Diversion Pipes In Open Channels: Large Flume Experiments, Ali Ercan, M. Levent Kavvas, Kara Carr, Zachary Hockett, Houssein Bandeh, Timothy D. Mussen, Dennis E. Cocherell, Jamilynn B. Poletto, Joseph J. Cech Jr., Nann A. Fangue

School of Natural Resources: Faculty Publications

Most of the water diversions on the Sacramento and San Joaquin Rivers (California, United States) and their tributaries are currently unscreened. These unscreened diversions are commonly used for irrigation and are potentially harmful to migrating and resident fishes. A large flume (test section: 18.29 m long, 3.05 m wide and 3.20 m high) was used to investigate the hydraulic fields near an unscreened water diversion under ecologically and hydraulically relevant diversion rates and channel flow characteristics. We investigated all combinations of three diversion rates (0.28, 0.42, and 0.57 m³/s) and three sweeping velocities (0.15, 0.38, and 0.61 m/s), …

A Comparison Of Grid-Based And Sph Binary Mass-Transfer And Merger Simulations, Patrick M. Motl, Juhan Frank, Jan Staff, Geoffrey C. Clayton, Christopher L. Fryer, Wesley Even, Steven Diehl, Joel E. Tohline

Faculty Publications

There is currently a great amount of interest in the outcomes and astrophysical implications of mergers of double degenerate binaries. In a commonly adopted approximation, the components of such binaries are represented by polytropes with an index of n = 3/2. We present detailed comparisons of stellar mass-transfer and merger simulations of polytropic binaries that have been carried out using two very different numerical algorithms - a finite-volume "grid" code and a smoothed-particle hydrodynamics (SPH) code. We find that there is agreement in both the ultimate outcomes of the evolutions and the intermediate stages if the initial conditions for each …

How Hospitable Are Space Weather Affected Habitable Zones? The Role Of Ion Escape, Vladimir S. Airapetian, Alex Glocer, George V. Khazanov, Robert O Parke Loyd, Kevin France, Jan Josef Sojka, William C. Danchi, Michael W. Liemohn

All Physics Faculty Publications

Atmospheres of exoplanets in the habitable zones around active young G-K-M stars are subject to extreme X-ray and EUV (XUV) fluxes from their host stars that can initiate atmospheric erosion. Atmospheric loss affects exoplanetary habitability in terms of surface water inventory, atmospheric pressure, the efficiency of greenhouse warming, and the dosage of the UV surface irradiation. Thermal escape models suggest that exoplanetary atmospheres around active K-M stars should undergo massive hydrogen escape, while heavier species including oxygen will accumulate forming an oxidizing atmosphere. Here, we show that non-thermal oxygen ion escape could be as important as thermal, hydrodynamic H escape …

Dynamic Fluctuations From Hydrodynamics And Kinetic Theory In High Energy Collisions, Christopher David Zin

Wayne State University Dissertations

It is well accepted that heavy ion collisions can be described using hydrodynamic theory, implying these systems are large enough and long lived enough to reach local equilibrium. Recent measurements of correlations in pA and high multiplicity pp collisions at the Relativistic Heavy Ion Collider and Large Hadron Collider have shown that these systems also exhibit signs of thermalization, unexpected in the smaller, shorter lived systems. Studying this behavior can give insight into the thermalization process and help clarify the relationship between flow in large systems and hydrodynamics. In an effort to understand these measurements we use the Boltzmann equation, …

Impact Of Vertical Internals On The Hydrodynamics And Heat Transfer Coefficient In A Gas-Solid Fluidized Bed, Haidar Moafaq Taofeeq

Doctoral Dissertations

"This research studied the impact of the dense vertical immersed heat exchanging tubes on the gas and solids hydrodynamic characteristics, flow regime, pressure drop, and heat transfer in a 0.14 m inside diameter gas-solid fluidized bed column of. Two sizes of vertical internal tube bundles (0.0127 and 0.0254 m) of circular arrangement have been implemented to represent the heat exchange tubes covering 25% of the column cross-sectional area. The experimental work was achieved at different operating conditions and various solids particle types that differ in average particle size, solids density, particles shape, and particles sphericity. The experimental measurements were performed …

Numerical Simulations Of Mass Transfer In Close And Contact Binaries Using Bipolytropes, Kundan Vaman Kadam

LSU Doctoral Dissertations

We present the first self-consistent, three dimensional study of hydrodynamic simulations of mass transfer in close and contact binary systems, with both stars represented as bipolytropes (composite polytopes). The project is motivated by the recent eruption of V1309 Scorpii which was proved to be the merger of a contact binary system. The final eruption is assumed to be the disruption of the core of the secondary inside the more massive star. The initial, equilibrium binary models are rotating synchronously in circular orbits and are obtained using the Bipolytropic Self Consistent Field (BSCF) technique, which is a modi cation of Hachisu's …

Characterizing The Hydrodynamics Of A Meandering River Neck Cutoff, Christopher Turnipseed

LSU Master's Theses

Meandering river systems often experience a geomorphic phenomenon known as a neck cutoff. The White River of Arkansas has recently undergone several neck cut offs, which have provided a unique opportunity to collect field measurements of the first two years after the opening of the cutoff. In this study the field data was complemented with hydrodynamic simulations to assess the significance of different flow conditions. The findings suggest that flood events play a substantial role in the geomorphic adjustment of the river to the cutoff.