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 Title
 Gravitational signature of corecollapse supernova results of CHIMERA simulations.
 Creator
 Yakunin, Konstantin., Charles E. Schmidt College of Science, Department of Physics
 Abstract/Description

Corecollapse supernovae (CCSN) are among the most energetic explosions in the universe, liberating ~1053 erg of gravitational binding energy of the stellar core. Most of this energy ( ~99%) is emitted in neutrinos and only 1% is released as electromagnetic radiation in the visible spectrum. Energy radiated in the form of gravitational waves (GWs) is about five orders smaller. Nevertheless, this energy corresponds to a very strong GW signal and, because of this CCSN are considered as one of...
Show moreCorecollapse supernovae (CCSN) are among the most energetic explosions in the universe, liberating ~1053 erg of gravitational binding energy of the stellar core. Most of this energy ( ~99%) is emitted in neutrinos and only 1% is released as electromagnetic radiation in the visible spectrum. Energy radiated in the form of gravitational waves (GWs) is about five orders smaller. Nevertheless, this energy corresponds to a very strong GW signal and, because of this CCSN are considered as one of the prime sources of gravitational waves for interferometric detectors. Gravitational waves can give us access to the electromagnetically hidden compact inner core of supernovae. They will provide valuable information about the angular momentum distribution and the baryonic equation of state, both of which are uncertain. Furthermore, they might even help to constrain theoretically predicted SN mechanisms. Detection of GW signals and analysis of the observations will require realistic signal predi ctions from the nonparameterized relativistic numerical simulations of CCSN. This dissertation presents the gravitational wave signature of corecollapse v supernovae. Previous studies have considered either parametric models or nonexploding models of CCSN. This work presents complete waveforms, through the explosion phase, based on firstprinciples models for the first time. We performed 2D simulations of CCSN using the CHIMERA code for 12, 15, and 25M nonrotating progenitors. CHIMERA incorporates most of the criteria for realistic corecollapse modeling, such as multifrequency neutrino transport coupled with relativistic hydrodynamics, eective GR potential, nuclear reaction network, and an industrystandard equation of state., Based on the results of our simulations, I produced the most realistic gravitational waveforms including all postbounce phases of corecollapse supernovae: the prompt convection, the stationary accretion shock instability, and the corresponding explosion. Additionally, the tracer particles applied in the analysis of the GW signal reveal the origin of lowfrequency component in the prompt part of gravitational waveform. Analysis of detectability of the GW signature from a Galactic event shows that the signal is within the bandpass of current and future GW observatories such as AdvLIGO, advanced Virgo, and LCGT.
Show less  Date Issued
 2011
 PURL
 http://purl.flvc.org/FAU/3322512
 Subject Headings
 Mathematical physics, Continuum mechanics, Supernovae, Mathematical models
 Format
 Document (PDF)
 Title
 Effects of Granulometric Parameters and Mix Proportions on the Shear Strength of Binary Granular Mixtures.
 Creator
 Gonzalez Moya, Daniel E., Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
 Abstract/Description

Geotechnical engineers are commonly faced with the need to perform ground improvement techniques to achieve the necessary bearing capacity for a project. Some of the most common techniques involve the excavation and replenishment of problematic geomaterial with one of better quality. Common projects, such as road embankments and retaining walls, also require the selection of backfill material. The guidelines for selecting backfill material are typically limited to complying with certain...
Show moreGeotechnical engineers are commonly faced with the need to perform ground improvement techniques to achieve the necessary bearing capacity for a project. Some of the most common techniques involve the excavation and replenishment of problematic geomaterial with one of better quality. Common projects, such as road embankments and retaining walls, also require the selection of backfill material. The guidelines for selecting backfill material are typically limited to complying with certain gradation bands, relative densities and allowable fines content. Roundgrained silica sand, and beach sand from Boca Raton, FL, were used to generate a total of 16 binary granular mixtures containing different amounts of finer material, for which a series of direct shear tests were conducted. Based on the experimental results, it may be possible to provide an alternative criteria for selecting backfill material based on granulometric parameters and the amount of finer material.
Show less  Date Issued
 2016
 PURL
 http://purl.flvc.org/fau/fd/FA00004714, http://purl.flvc.org/fau/fd/FA00004714
 Subject Headings
 Continuum mechanics, Geotechnical engineering, Granular materials  Dynamic testing, Micromechanics  Mathematical models, Soil liquefaction
 Format
 Document (PDF)
 Title
 Internal waves on a continental shelf.
 Creator
 Jagannathan, Arjun., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

In this thesis, a 2D CHebyshev spectral domain decomposition method is developed for simulating the generation and propagation of internal waves over a topography. While the problem of stratified flow over topography is by no means a new one, many aspects of internal wave generation and breaking are still poorly understood. This thesis aims to reproduce certain observed features of internal waves by using a Chebyshev collation method in both spatial directions. The numerical model solves the...
Show moreIn this thesis, a 2D CHebyshev spectral domain decomposition method is developed for simulating the generation and propagation of internal waves over a topography. While the problem of stratified flow over topography is by no means a new one, many aspects of internal wave generation and breaking are still poorly understood. This thesis aims to reproduce certain observed features of internal waves by using a Chebyshev collation method in both spatial directions. The numerical model solves the inviscid, incomprehensible, fully nonlinear, nonhydrostatic Boussinesq equations in the vorticitystreamfunction formulation. A number of important features of internal waves over topography are captured with the present model, including the onset of wavebreaking at subcritical Froude numbers, up to the point of overturning of the pycnoclines. Density contours and wave spectra are presented for different combinations of Froude numbers, stratifications and topographic slope.
Show less  Date Issued
 2012
 PURL
 http://purl.flvc.org/FAU/3358549
 Subject Headings
 Engineering geology, Mathematical models, Chebyshev polynomials, Fluid dynamics, Continuum mechanics, Spectral theory (Mathematics)
 Format
 Document (PDF)
 Title
 Subjecting the CHIMERA supernova code to two hydrodynamic test problems, (i) Riemann problem and (ii) Point blast explosion.
 Creator
 Ahsan, Abu Salah M., Charles E. Schmidt College of Science, Department of Physics
 Abstract/Description

A Shock wave as represented by the Riemann problem and a Pointblast explosion are two key phenomena involved in a supernova explosion. Any hydrocode used to simulate supernovae should be subjected to tests consisting of the Riemann problem and the Pointblast explosion. L. I. Sedov's solution of Pointblast explosion and Gary A. Sod's solution of a Riemann problem have been rederived here from one dimensional fluid dynamics equations . Both these problems have been solved by using the idea...
Show moreA Shock wave as represented by the Riemann problem and a Pointblast explosion are two key phenomena involved in a supernova explosion. Any hydrocode used to simulate supernovae should be subjected to tests consisting of the Riemann problem and the Pointblast explosion. L. I. Sedov's solution of Pointblast explosion and Gary A. Sod's solution of a Riemann problem have been rederived here from one dimensional fluid dynamics equations . Both these problems have been solved by using the idea of Selfsimilarity and Dimensional analysis. The main focus of my research was to subject the CHIMERA supernova code to these two hydrodynamic tests. Results of CHIMERA code for both the blast wave and Riemann problem have then been tested by comparing with the results of the analytic solution.
Show less  Date Issued
 2008
 PURL
 http://purl.flvc.org/FAU/172665
 Subject Headings
 Mathematical physics, Continuum mechanics, Number theory, Supernovae, Data processing, Shock waves, Fluid dynamics
 Format
 Document (PDF)