Physical Sciences and Mathematics Commons^™

The Physical Origin Of Negative Superhumps In Cataclysmic Variables, Matt A. Wood, Christopher J. Burke

Aerospace, Physics, and Space Science Faculty Publications

It has been suspected for over 20 years that the observed negative superhumps in cataclysmic variables are due to the retrograde precession of a tilted disk. We present new smooth particle hydrodynamics simulation results that demonstrate that the source of the modulation of the luminosity of the light in a negatively superhumping cataclysmic variable is the transit of the bright spot across the face of an accretion disk that is tilted out of the orbital plane. In an untilted disk the bright spot is always located on the outer edge of the disk, and the intrinsic brightness of the accretion …

Numerical Hydrodynamics Of Relativistic Extragalactic Jets, Eunwoo Choi

Physics and Astronomy Dissertations

This dissertation describes a multidimensional relativistic hydrodynamic code which solves the special relativistic hydrodynamic equations as a hyperbolic system of conservation laws based on the total variation diminishing (TVD) scheme. Several standard tests and test simulations are presented to demonstrate the accuracy, robustness and flexibility of the code. Using this code we have studied three-dimensional hydrodynamic interactions of relativistic extragalactic jets with two-phase ambient media. The deflection angle of the jet is influenced more by the density contrast of the cloud than by the beam Mach number of the jet, and a relativistic jet with low relativistic beam Mach number …

A Dyad Theory Of Hydrodynamics And Electrodynamics, Preston Jones

Publications

The dyadic calculus is developed in a form suitable for the description of physical relations in curved space. The 4-space equations of hydrodynamics and electrodynamics are constructed using this dyadic calculus. As a demonstration of the relationship between gravity and electrodynamics a time varying metric is shown to generate electromagnetic radiation.

Algorithm Refinement For Fluctuating Hydrodynamics, Alejandro Garcia, S. Williams, J. B. Bell

Faculty Publications

This paper introduces an adaptive mesh and algorithm refinement method for fluctuating hydrodynamics. This particle-continuum hybrid simulates the dynamics of a compressible fluid with thermal fluctuations. The particle algorithm is direct simulation Monte Carlo (DSMC), a molecular-level scheme based on the Boltzmann equation. The continuum algorithm is based on the Landau–Lifshitz Navier–Stokes (LLNS) equations, which incorporate thermal fluctuations into macroscopic hydrodynamics by using stochastic fluxes. It uses a recently developed solver for the LLNS equations based on third-order Runge–Kutta. We present numerical tests of systems in and out of equilibrium, including time-dependent systems, and demonstrate dynamic adaptive refinement by the …

Algorithm Refinement For Fluctuating Hydrodynamics, Alejandro Garcia, Sarah Williams, John B. Bell

Alejandro Garcia

This paper introduces an adaptive mesh and algorithm refinement method for fluctuating hydrodynamics. This particle-continuum hybrid simulates the dynamics of a compressible fluid with thermal fluctuations. The particle algorithm is direct simulation Monte Carlo (DSMC), a molecular-level scheme based on the Boltzmann equation. The continuum algorithm is based on the Landau–Lifshitz Navier–Stokes (LLNS) equations, which incorporate thermal fluctuations into macroscopic hydrodynamics by using stochastic fluxes. It uses a recently developed solver for the LLNS equations based on third-order Runge–Kutta. We present numerical tests of systems in and out of equilibrium, including time-dependent systems, and demonstrate dynamic adaptive refinement by the …

Quantization In Astrophysics, Brownian Motion, And Supersymmetry, Florentin Smarandache, Victor Christianto

Branch Mathematics and Statistics Faculty and Staff Publications

The present book discusses, among other things, various quantization phenomena found in Astrophysics and some related issues including Brownian Motion. With recent discoveries of exoplanets in our galaxy and beyond, this Astrophysics quantization issue has attracted numerous discussions in the past few years. Most chapters in this book come from published papers in various peer-reviewed journals, and they cover different methods to describe quantization, including Weyl geometry, Supersymmetry, generalized Schrödinger, and Cartan torsion method. In some chapters Navier-Stokes equations are also discussed, because it is likely that this theory will remain relevant in Astrophysics and Cosmology While much of the …

Microscopic-Macroscopic Simulations Of Rigid-Rod Polymer Hydrodynamics: Heterogeneity And Rheochaos, M. Gregory Forest, Ruhai Zhou, Qi Wang

Mathematics & Statistics Faculty Publications

Rheochaos is a remarkable phenomenon of nematic (rigid-rod) polymers in steady shear, with sustained chaotic fluctuations of the orientational distribution of the rod ensemble. For monodomain dynamics, imposing spatial homogeneity and linear shear, rheochaos is a hallmark prediction of the Doi-Hess theory [M. Doi, J. Polym. Sci. Polym. Phys. Ed., 19 (1981), pp. 229-243; M. Doi and S. F. Edwards, The Theory of Polymer Dynamics, Oxford University Press, London, New York, 1986; S. Hess, Z. Naturforsch., 31 (1976), pp. 1034-1037. The model behavior is robust, captured by second-moment tensor approximations G. Rienäcker, M. Kröger, and S. Hess, Phys. Rev. …

Exchange Hydrodynamics Between A Subestuary And Its Adjacent Estuary, Diego A. Narváez

OES Theses and Dissertations

Four oceanographic surveys and two periods of moored data were analyzed to describe the subtidal exchange hydrodynamics between a subestuary (Nansemond River) and its adjacent estuary (James River) in the lower Chesapeake Bay. The surveys were carried out during two semidiurnal periods (~25 hrs), which included two spring and two neap tides. Velocity profiles and hydrographic data were recorded over an area ~4 km long and ~1 km wide allowing a spatial resolution rarely obtained with observational data. The results obtained in the surveys were extended with instruments deployed at the entrance to the subestuary during winter and summer time …

Heliospheric Response To Different Possible Interstellar Environments, Hans-Reinhard Muller, Priscilla C. Frisch, Vladimir Florinski, Gary P. Zank

Dartmouth Scholarship

At present, the heliosphere is embedded in a warm, low-density interstellar cloud that belongs to a cloud system flowing through the local standard of rest with a velocity near ~18 km s^-1. The velocity structure of the nearest interstellar material (ISM), combined with theoretical models of the local interstellar cloud (LIC), suggest that the Sun passes through cloudlets on timescales of ≤10³-10⁴ yr, so the heliosphere has been, and will be, exposed to different interstellar environments over time. By means of a multifluid model that treats plasma and neutral hydrogen self-consistently, the interaction of the …

Hole Dynamics In Polymer Langmuir Films, James C. Alexander, Andrew J. Bernoff, Elizabeth K. Mann, J. Adin Mann Jr., Lu Zou

All HMC Faculty Publications and Research

This article develops a model for the closing of a gaseous hole in a liquid domain within a two-dimensional fluid layer coupled to a Stokesian subfluid substrate, and compares this model to experiments following hole dynamics in a polymer Langmuir monolayer. Closure of such a hole in a fluid layer is driven by the line tension at the hole boundary and the difference in surface pressure within the hole and far outside it. The observed rate of hole closing is close to that predicted by our model using estimates of the line tension obtained by other means, assuming that the …

Hydrodynamic Mediation Of Density-Dependent Growth And Adult-Juvenile Interactions Of A Spionid Polychaete, Brent T. Hentschel, Amy A. Larson

Environmental Science and Management Faculty Publications and Presentations

Abstract We performed an experiment to test the effects of adult density on the growth rates of juvenile Polydora cornuta. Our experiment was performed in three identical counter-rotating annular flumes, each set to one of three different flow speeds for a period of 3 d (U 5mm = 3, 6, or 12 cm s^-1 , where U_5mm = velocity measured 5 mm above bottom). We implanted replicate vials containing a premeasured juvenile P. cornuta and either 0, 2, or 5 adults into a 2-cm layer of sediment in the flume. The relative growth rates of the juveniles …

Estimating Hydrodynamic Quantities In The Presence Of Microscopic Fluctuations, Alejandro Garcia

Faculty Publications

This paper discusses the evaluation of hydrodynamic variables in the presence of spontaneous fluctuations, such as in molecular simulations of fluid flows. The principal point is that hydrodynamic variables such as fluid velocity and temperature must be defined in terms of mechanical variables such as momentum and energy density). Because these relations are nonlinear and because fluctuations of mechanical variables are correlated, care must be taken to avoid introducing a bias when evaluating means, variances, and correlations of hydrodynamic variables. The unbiased estimates are formulated; some alternative, incorrect approaches are presented as cautionary warnings. The expressions are verified by numerical …

Star Formation And Feedback In Smoothed Particle Hydrodynamic Simulations - I. Isolated Galaxies, G Stinson, A Seth, N Katz, J Wadsley, F Governato, T Quinn

Astronomy Department Faculty Publication Series

We present an analysis of star formation and feedback recipes appropriate for galactic smoothed particle hydrodynamics simulations. Using an isolated Milky Way-like galaxy, we constrain these recipes based on well-established observational results. Our star formation recipe is based on that of Katz with the additional inclusion of physically motivated supernova feedback recipes. We propose a new feedback recipe in which Type II supernovae are modelled using an analytical treatment of blastwaves. With this feedback mechanism and a tuning of other star formation parameters, the star formation in our isolated Milky Way-like galaxy follows the slope and normalization of the observed …

Dq Herculis In Profile: Whole Earth Telescope Observations And Smoothed Particle Hydrodynamics Simulations Of An Edge-On Cataclysmic Variable System, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

The old nova DQ Herculis was the Whole Earth Telescope Northern Hemisphere target for the 1997 July campaign and was observed on four nights with the SARA 0.9 m telescope during 2003 June. We present updated ephemerides for the eclipse and 71 s timings. The Fourier transform displays power at the presumed white dwarf spin period of 71.0655 s, but no significant power at either 142 or 35.5 s. The mean pulsed light curve is obtained by folding on the orbital period modulus the mean ephemeris of the 71 s period, and from this we calculate an O - C …

Model Simulations Of A Shock‐Cloud Interaction In The Cygnus Loop, Daniel J. Patnaude, Robert A. Fesen

Dartmouth Scholarship

We present optical observations and two-dimensional hydrodynamic modeling of an isolated shocked ISM cloud. Hα images taken in 1992.6 and 2003.7 of a small optical emission cloud along the southwestern limb of the Cygnus Loop were used to measure positional displacements of ~01 yr^-1 for surrounding Balmer-dominated emission filaments and 0025-0055 yr^-1 for internal cloud emission features. These measurements imply transverse velocities of 250 and 80-140 km s^-1 for ambient ISM and internal cloud shocks, respectively. A lack of observed turbulent gas stripping at the cloud-ISM boundary in the Hα images suggests that there is not an …

Self-Consistent Dynamic Models Of Steady Ionization Fronts. I. Weak-D And Weak-R Fronts, W. J. Henney, S. J. Arthur, R. J. R. Williams, Gary J. Ferland

Physics and Astronomy Faculty Publications

We present a method for including steady state gas flows in the plasma physics code Cloudy, which was previously restricted to modeling static configurations. The numerical algorithms are described in detail, together with an example application to plane-parallel ionization-bounded H II regions. As well as providing the foundation for future applications to more complex flows, we find the following specific results regarding the effect of advection on ionization fronts in H II regions: (1) Significant direct effects of advection on the global emission properties occur only when the ionization parameter is lower than is typical for H II regions. For …

The Dyad Theory Of Classical And Quantum Physics, Preston Jones

Publications

The 4-space equations of hydrodynamics, electrodynamics, and quantum mechanics are developed using the dyad calculus. Gravity is found to couple hydrodynamics, electrodynamics, and quantum mechanics through the 4- space metric and differential operator. Expanding the 4-space equations of electrodynamics a time varying metric is shown to dissipate electromagnetic energy.

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The corrosion of structural materials is a major concern for the use of lead-bismuth eutectic (LBE) systems for nuclear applications such as in transmuter targets or fast reactors. Corrosion in liquid metal systems can occur through various processes, including, for example, dissolution, formation of inter-metallic compounds at the interface, and penetration of liquid metal along grain boundaries. Predicting the rate of these processes depends on numerous system operational factors: temperature, system geometry, thermal gradients, solid and liquid compositions, and velocity of the liquid metal, to name a few. Corrosion, along with mechanical and/or hydraulic factors, often contributes to component failure. …

An Exercise In Forecasting Loop Current And Eddy Frontal Positions In The Gulf Of Mexico, Lie-Yauw Oey, Tal Ezer, George Forristall, C. Cooper, Steven Dimarco, S. Fan

CCPO Publications

As part of a model-evaluation exercise to forecast Loop Current and Loop Current eddy frontal positions in the Gulf of Mexico, the Princeton Regional Ocean Forecast System (PROFS) is tested to forecast 14 4-week periods Aug/25/99- Sep/20/00, during which a powerful eddy, Eddy Juggernaut (Eddy-J) separated from the Loop Current and propagated southwestward. To initialize each forecast, PROFS assimilates satellite sea surface height (SSH) anomaly and temperature (SST) by projecting them into subsurface density using a surface/subsurface correlation that is a function of the satellite SSH anomaly. The closest distances of the forecast fronts from seven fixed stations in the …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Trp Final Report 09/01/2003-08/31/2004, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the TRP proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Fourth Quarterly Report 06/01/2004-08/31/2004, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the TRP proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Third Quarterly Report 03/01/2004-05/31/2004, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the TRP proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: First Quarterly Report 01/12/04-02/29/04, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the TRP proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The corrosion of structural materials is a major concern for the use of lead-bismuth eutectic (LBE) systems for nuclear applications such as in transmuter targets or fast reactors. Corrosion in liquid metal systems can occur through various processes, including, for example, dissolution, formation of inter-metallic compounds at the interface, and penetration of liquid metal along grain boundaries. Predicting the rate of these processes depends on numerous system operational factors: temperature, system geometry, thermal gradients, solid and liquid compositions, and velocity of the liquid metal, to name a few. Corrosion, along with mechanical and/or hydraulic factors, often contributes to component failure. …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Fourth Quarterly Report 09/01/2003-11/30/2003, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the TRP proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Fourth Quarterly Report 06/01/2003-08/30/2003, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the TRP proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: Annual Report -Phase Ii 09/01/2002-08/30/2003, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the TRP proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics - Phase Three, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The proposed work will combine chemical kinetics and hydrodynamics in target and test-loop lead-bismuth eutectic (LBE) systems to model system corrosion effects. This approach will result in a predicative tool that can be validated with corrosion test data, used to systematically design tests and interpret the results, and provide guidance for optimization in LBE system designs. The task includes two subtasks. The first subtask is to try to develop the necessary predictive tools to be able to predict the levels of oxygen and corrosion products close to the boundary layer through the use of Computational Fluid Dynamics (CFD) modeling. The …

Quarterly Report For The Trp Project, March–June 2003, Samir Moujaes, Yitung Chen, Kanthi Kiran Daiska, Chao Wu

Transmutation Sciences Materials (TRP)

The MTL is assumed to be a 5m long rectangular loop with a circular cross-section. Because of the non-symmetry, and due to the active participation of the secondary flows due to the elbows present in the rectangular loop model, the geometry is considered as a 3D model.

When the regions of maximum corrosion and precipitation are compared, they fall in the same zone for both the analytical and simulated models. The reason for a larger concentration flux in the case of turbulent flow than for the laminar flow can be explained by the concept of higher lateral diffusion in the …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics: Quarterly Progress Report 12/1/02- 2/28/03, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the AAA proposed application.

Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with very limited density. The transport of oxygen and corrosion products, their interaction and variation of corrosion/precipitation along the flow are not well understood.

The first subtask of this project involves using a …