Time Symmetry Breaking In Turbulent Multi Particle Dispersion

This thesis presents experimental and theoretical investigations of the connection between the time asymmetry in the short-time evolution of particle clusters and the intrinsic irreversibility of turbulent flows due to the energy cascade. The term turbulence describes a special state of a continuous medium in which many interacting degrees of freedom are excited. One of the interesting phenomena observed in turbulent flows is their time irreversibility. When milk is stirred into coffee, for example, highly complex and interwoven structures are produced, making the mixing process irreversible. This behavior can be analyzed in more detail by studying the dispersion of particle clusters. Previous experimental and numerical studies on the time asymmetry in two-particle dispersion indicate that particles separate faster backwards than forwards in time, but no conclusive explanation has yet been provided. In this thesis, an experimental study on the short-time behavior of two- and four-particle dispersion in a turbulent water flow between two counter-rotating propellers is presented. A brief but rigorous theoretical analysis reveals that the observed time irreversibility is closely linked to the turbulence energy cascade. Additionally, it is demonstrated experimentally that the addition of minute amounts of polymers to the flow has a significant impact on multi-particle dispersion due to an alteration of the energy cascade.

This thesis presents experimental and theoretical investigations of the connection between the time asymmetry in the short-time evolution of particle clusters and the intrinsic irreversibility of turbulent flows due to the energy cascade. The term turbulence describes a special state of a continuous medium in which many interacting degrees of freedom are excited. One of the interesting phenomena observed in turbulent flows is their time irreversibility. When milk is stirred into coffee, for example, highly complex and interwoven structures are produced, making the mixing process irreversible. This behavior can be analyzed in more detail by studying the dispersion of particle clusters. Previous experimental and numerical studies on the time asymmetry in two-particle dispersion indicate that particles separate faster backwards than forwards in time, but no conclusive explanation has yet been provided. In this thesis, an experimental study on the short-time behavior of two- and four-particle dispersion in a turbulent water flow between two counter-rotating propellers is presented. A brief but rigorous theoretical analysis reveals that the observed time irreversibility is closely linked to the turbulence energy cascade. Additionally, it is demonstrated experimentally that the addition of minute amounts of polymers to the flow has a significant impact on multi-particle dispersion due to an alteration of the energy cascade.

The phenomenon of dynamical symmetry breaking (DSB) in quantum field theory is discussed in a detailed and comprehensive way. The deep connection between this phenomenon in condensed matter physics and particle physics is emphasized. The realizations of DSB in such realistic theories as quantum chromodynamics and electroweak theory are considered. Issues intimately connected with DSB such as critical phenomenona and effective lagrangian approach are also discussed.

Discusses mirror symmetry, a symmetries, time reversal, vacuum as a physical medium, spontaneous symmetry breaking, particles, and quarks.

This book is a collection of original papers on dynamical gauge symmetry breaking, and is intended for graduate students and researchers in theoretical physics (elementary particle physics and others) who have an understanding of basic quantum field theory. The book can serve as a research text for those requiring an introduction to dynamical gauge symmetry breaking and as a reference text for active researchers. The important papers in the field that are included deal with attempts to apply the ideas to realistic models of elementary particle interactions. A historical critique by the editors provides an introductory review.

The transport of heavy, polydispersed particles and the inter-phase transfer of kinetic energy is measured experimentally in a turbulent shear layer. Specifically, fundamental/subharmonic forcing and conditional-averaging techniques were used to study the particle/turbulence interaction with the large-scale, spanwise, coherent vortices, starting from their initial roll-up through the first pairing event. It is shown that the pairing event plays a homogenizing role on the particulate field, but the amount of homogenization is strongly dependent upon the particle's viscous relaxation time, the eddy turnover time, as well as the time the particles are allowed to interact with each scale prior to a pairing event. Thus, even though the smaller size particles become well-mixed across the structure, the larger sizes are still dispersed in an inhomogeneous fashion. The dispersed/carrier phase coupling was examined through the measurement of conditionally-averaged kinetic energy transfer (which results from the work done to accelerate or decelerate the dispersed phase), as well as the conditionally-averaged particle dissipation (energy dissipated by shear deformation in the carrier phase due to the relative slip between the particles and the carrier fluid).

This book contains selected papers of Prof Nambu who is one of the most original and outstanding particle theorists of our time. This volume consists of about 40 papers which made fundamental contributions to our understanding of particle physics during the last few decades. The unpublished lecture note on string theory (1969) and the first paper on spontaneous symmetry breaking (1961) are retyped and included. The book also contains a memoir of Prof Nambu on his research career. Contents:A Note on the Eigenvalue Problem in Crystal StatisticsThe Use of the Proper Time in Quantum Electrodynamics IPossible Existence of a Heavy Neutral MesonParametric Representations of General Green's FunctionsDispersion Relations for Form FactorsAxial Vector Current Conservation in Weak InteractionsA ‘Superconductor’ Model of Elementary Particles and Its ConsequencesDynamical Model of Elementary Particles Based on an Analogy with Superconductivity I (with G Jona-Lasinio)Chirality Conservation with Soft Pion Production (with D Lurié)Infinite MultipletsS-Matrix in Semiclassical ApproximationQuark Model and the Factorization of Veneziano AmplitudeDuality and HadrodynamicsGeneralized Hamiltonian DynamicsStrings, Vortices and Gauge FieldsBCS Mechanism, Quasi-Supersymmetry and the Fermion Massesand other papers Readership: High energy physicists. keywords: “The book benefits from the inclusion of previously unpublished material, informal lectures and conference-summary talks that are not widely available. These, together with the selected research papers, provide an excellent scientific biography of Nambu and of the Japanese physics tradition, which he describes in several places … it is in the less formal presentations that the motivation for Nambu's ideas, as well as his charming modesty, become evident and make reading this collection the pleasure that it is.” Physics Today “In the citation of Nobel physics prize committee, Nambu's unpublished paper presented at Mid West Conference at Purdue University in 1960 is referred to as the original article on spontaneously broken symmetry. This is the paper which we have decided to include in the volume ‘Broken Symmetry’ because of its historical importance. The paper would have been inaccessible and may not have been noticed by the general public if it were not retyped and included in the volume.” T Eguchi and K Nishijima Editors

The transport of bacteria in turbulent river-like environments is addressed, where bacterial populations are frequently encountered attached to solids. This transport mode is investigated by studying the transient settling of heavy particles in turbulent channel flows featuring sediment beds. A numerical method is used to fully resolve turbulence and finite-size particles, which enables the assessment of the complex interplay between flow structures, suspended solids and river sediment.