Complex Temporal and Spatial Patterns in Nonequilibrium Systems


Book Description

Dynamical systems methods are being developed and used to characterize the formation and evolution of temporal and spatial patterns in systems maintained far from equilibrium. In particular, experiments and analyses are considering electrodeposition of fractal metallic clusters, pattern formation in reaction-diffusion systems, and the primary instabilities of some fluid flows. Novel reactors have been developed to search for chemical patterns (spatial variations in the chemical composition), and sustained patterns have been found in several different one- and two-dimensional geometries. Bifurcations in these patterns are studied by varying control parameters, e.g., the concentrations of the feed chemicals or the temperature. The observed two-dimensional chemical patterns range from the stationary patterns, similar to those predicted by Turing in 1952 but not observed until 1990, to chemical turbulence, which is characterized by large numbers of defects and a rapid decay of spatial correlations. These provide general insights into the formation of spatiotemporal patterns in nonequilibrium systems.







Complex Temporal and Spatial Patterns in Nonequilibrium Processes. Final Report, December 1, 1987--November 30, 1992


Book Description

Dynamical systems methods have been used to study bifurcations and pattern formation in nonequilibrium systems. Accomplishments during this period include: information-theoretic methods for analyzing chaos, chemical reactors for studying sustained reaction-diffusion patterns, a reactor exploiting pattern formation to extract short- lived intermediate species, observation of bifurcation from periodic to quasiperiodic rotating chemical spiral patterns, observation of a Turing bifurcation (transition from uniform state to a stationary chemical pattern), method for extracting noise strength in ramped convection, self-similar fractal structure of Zn clusters in electrodeposition, and dynamical instability in crack propagation.




Pattern Formation and Dynamics in Nonequilibrium Systems


Book Description

An account of how complex patterns form in sustained nonequilibrium systems; for graduate students in biology, chemistry, engineering, mathematics, and physics.




Pattern Formation and Dynamics in Nonequilibrium Systems


Book Description

Many exciting frontiers of science and engineering require understanding the spatiotemporal properties of sustained nonequilibrium systems such as fluids, plasmas, reacting and diffusing chemicals, crystals solidifying from a melt, heart muscle, and networks of excitable neurons in brains. This introductory textbook for graduate students in biology, chemistry, engineering, mathematics, and physics provides a systematic account of the basic science common to these diverse areas. This book provides a careful pedagogical motivation of key concepts, discusses why diverse nonequilibrium systems often show similar patterns and dynamics, and gives a balanced discussion of the role of experiments, simulation, and analytics. It contains numerous worked examples and over 150 exercises. This book will also interest scientists who want to learn about the experiments, simulations, and theory that explain how complex patterns form in sustained nonequilibrium systems.




Some Problems on Spatial Patterns in Nonequilibrium Systems


Book Description

In this thesis, we study the evolution of spatial patterns in two nonequilibrium systems. In Chapter 1, we study the steady state of a 1-d cellular automata (CA) model of chemical turbulence. Empirically there are two interesting types of space-time patterns (depending on model parameters): a S phase which seems to contain solitons and a T phase which seems to be turbulent. We show that the macroscopic phases can be predicted from the microscopic dynamics. We define the thermodynamic limit of the steady state of CAs and show that the steady state of the S phase is trivial and the T phase exhibits a Gibbs state. We explicitly calculate the T phase steady state and find an approximate form for the energy functional which generates the Gibbs state. We show that there is no adequate characterization of turbulent behavior in CAs and introduce a quantity the "P-entropy" which is positive if the CA patterns are turbulent and zero otherwise. We show the P-entropy for the T phase is positive. In Chapter 2, we consider the consequences of the dynamical scaling hypothesis in phase ordering dynamics. We assume that the dynamics are governed by the Cahn-Hilliard-Cook (CHC) and time-dependent Ginzburg-Landau equations and show that the scaling hypothesis restricts the asymptotic growth rate of the length-scale of the patterns and the small wavevector behavior of the form factor. Specifically, if the form factor $Ssb{k}$($t$) grows as $ksp{delta}$ for small $delta$, then $deltageq$ 4 (for the CHC dynamics). We find that experimental data indicates $delta$ = 4. We also show that the CHC equation is sometimes inadequate for describing phase ordering dynamics. An alternative to the CHC model by Oono, Kitahara and Jasnow is examined. We find that many features of phase ordering dynamics are robust with respect to changing the dynamics.







Spatio-temporal Patterns In Nonequilibrium Complex Systems


Book Description

The purpose of the NATO Advanced Research Workshop, upon which this book is based, was to bring together experimentalists and theorists from many different fields, ranging from applied mathematics to materials science, but unified by their intrigue with nonlinear phenomena, in search of a deeper understanding of patterns in complex systems. To meet this goal, the participants made the effort to build bridges across canonical disciplinary boundaries by sharing what they thought was significant and relevant in search of the “truly significant simplicity of the basic laws of nature embedded in the amazing complexity of natural phenomena.” Spatio-Temporal Patterns in Nonequilibrium Complex Systems is one of the most exciting and fastest-growing branches of physics that impacts fields as diverse as new technologies and processes, economics and biology. Virtually every structure in our world, including ourselves, can be considered the result of a long sequence of successive symmetry-breaking instabilities due to nonlinear processes under nonequilibrium conditions of a complex system. While a scientific description of the spontaneous appearance of patterns in nature was first made by Johannes Kepler (1611), it has only been during the past twenty years that pattern formation, epitomized by the beautiful snowflakes that Kepler studied, has emerged as a science. Concepts and methods resulting from this dynamic new field will surely influence future developments in many disciplines.Complex systems, as studied in this book, are a good first step toward a description of the variety of phenomena included under the rubric “physics of complex systems.” Even the simplest of those presented here, liquid crystals, is still complex, but provides hints of essential ingredients needed to forge a fundamental understanding of nonequilibrium, nonlinear processes in the large. Fluid dynamics and turbulence, interface motion during solidification, autocatalytic chemical reactions, and pattern formation in biological systems play similar roles in other systems far from equilibrium.




Spatio-temporal Patterns In Nonequilibrium Complex Systems


Book Description

Details advances in complex systems, a branch of physics that impacts fields such as technologies and processes, economics and biology. The book explains how complex systems are a first step towards a description of the variety of phenomena included under the rubric physics of complex systems.