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result(s) for
"Nebus, Joseph"
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Vortex dynamics, statistical mechanics, and planetary atmospheres
by
Lim, Chjan C
,
Nebus, Joseph
,
Ding, Xueru
in
Applied Mathematics
,
Atmospheres
,
Computational Physics
2009
Vortex Dynamics, Statistical Mechanics, and Planetary Atmospheres introduces the reader with a background in either fluid mechanics or statistical mechanics to the modeling of planetary atmospheres by barotropic and shallow-water models. These potent models are introduced in both analytical and numerical treatments highlighting the ways both approaches inform and enlighten the other. This book builds on Vorticity, Statistical Mechanics, and Monte Carlo Simulations by Lim and Nebus in providing a rare introduction to this intersection of research fields. While the book reaches the cutting edge of atmospheric models, the exposition requires little more than an undergraduate familiarity with the relevant fields of study, and so this book is well suited to individuals hoping to swiftly learn an exciting new field of study. With inspiration drawn from the atmospheres of Venus and of Jupiter, the physical relevance of the work is never far from consideration, and the bounty of results shows a new and fruitful perspective with which to study planetary atmospheres.
Monte Carlo simulations, statistical mechanics, and ground states of the logarithmic potential
2002
The search for statistical equilibria at very low positive temperatures, using a Monte Carlo algorithm, can locate dynamical equilibria of the N-vortex problem on a sphere. Numerical results show this algorithm accurately and efficiently locates the lowest energy equilibrium. Using an essential tool called the radial distribution function, superficially similar configurations can be easily distinguished and classified. The problem of N bodies on the surface of the sphere interacting by a logarithmic potential is examined for selected N from 4 to 40,962, comparing the energies found by placing points at vertices of polyhedrons to the lowest energies found by a Monte Carlo algorithm. The polyhedron families are generated from simple polyhedrons through two triangular face splitting operations applied iteratively. The closest energy of these polyhedron configurations to the Monte Carlo minimum energy is identified and the energies agree well. The energy per particle pair asymptotically approaches a mean field theory limit of −½(log(2) − 1), approximately 0.153426, for both the polyhedron and the Monte Carlo-generated energies. On a mesh of N points distributed over the plane through methods like those employed above, the logarithmic potential is studied with the circulation is set to zero and the enstrophy held to a fixed value. Using a Monte Carlo Metropolis Rule-based algorithm to maximize the Gibbs factor exp(−β H), with β an inverse temperature and H the Hamiltonian, the arrangement of site vorticities is found to depend on the inverse temperature and number of points. From examining the effects the mesh size has by using the mean nearest neighbor parity introduced here, conclusions about the continuum limit can be drawn, and match analytical predictions that there are no phase transitions except at β = 0. Finally, meshes of N points are distributed over the unit sphere, and the logarithmic potential for this problem studied again with zero and fixed enstrophy. Through a similar Monte Carlo Metropolis algorithm the best arrangements of vorticities for mesh sizes and inverse temperatures are studied. Based on these results conclusions are drawn about the continuum limit, specifically that there are no phase transitions except at β = 0.
Dissertation
Planets and Inspiration
2009
The following sections are included:
Venus
Titan
The Great Red Spot
Polar Vortices and Other Curiosities
Outline
Book Chapter
The Monte Carlo Approach
2009
The following sections are included:
Introduction
Markov Chains
Detailed Balance
The Metropolis Rule
Multiple Canonical Constraints
Ensemble Averages
Metropolis-Hastings Monte Carlo Algorithm
Book Chapter
Extremal Free Energy in the Mean-Field Theory
2009
The following sections are included:
Introduction
Equilibrium Statistical Mechanics
Mean-Field Theory
Setting Up Coupled Barotropic Flows
Proofs for a Non-Rotating Planet
Mean-Field Theory on a Rotating Sphere
Positive Temperatures
Negative Temperatures
Book Chapter
Barotropic and Shallow-Water Models
2009
The following sections are included:
The Physical Model
Voronoi Cells and the Spin-Lattice Approximation
The Solid Sphere Model
The Shallow-Water Equations on the Rotating Sphere
The Spin-Lattice Shallow-Water Model
Circulation Constraints
Enstrophy Constraints
Gibbs Ensemble
Book Chapter
Dynamic Equilibria of the Barotropic Model — Variational Approach
2009
The following sections are included:
Energy-Relative Enstrophy Variational Theory
The Augmented Energy Functional
Extremals: Existence and Properties
Book Chapter
Phase Transitions of Barotropic Flow
2009
The following sections are included:
Introduction
Statistical Mechanics of Macroscopic Flows
Bragg-Williams Approximation
Internal Energy
Entropy
Helmholtz Free Energy
Polar State Criteria
The Non-Rotating Case
The Rotating Case
Summary of Main Results
The Infinite-Dimensional Non-Extensive Limit
Book Chapter
Phase Transitions to Super-Rotation — Exact Closed-Form Solutions
2009
The following sections are included:
Introduction
The Rotating Sphere Model
Solution of the Spherical Model
Book Chapter
The Shallow-Water Models — High Energy, Cyclonic Solutions
2009
The following sections are included:
Introduction
First Order Transitions
Antipodal Symmetry
Monte Carlo Results
Phase Transitions in Latent Heat
Conclusion
Book Chapter