Author: Bavand Keshavarz
Publisher:
ISBN:
Category :
Languages : en
Pages : 337
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Book Description
The fragmentation and breakup of complex fluids are fundamental elements of many industrial and biological processes. The fracture of food gels, atomization of paints, combustion of fuels containing anti-misting agents and application of pharmaceutical and agricultural sprays, as well as involuntary physiological processes such as sneezing, are common examples in which the atomized/fractured material contains synthetic or biological macromolecules that result in viscoelastic fluid characteristics. For many of these processes the effects of varying the rheological properties on the dynamics of fragmentation or fracture are still poorly understood. In this thesis, we investigate some of the underlying complexities associated with varying the rheology of such materials in both shear and elongation. The complex nonlinear rheology of these complex fluids under representative conditions of large strain and deformation rate is difficult to quantify experimentally and is a known challenge for existing constitutive models. The contribution of this thesis is therefore to develop and exploit several new experimental tools that enable precise rheological measurements under appropriate test conditions. A better experimental understanding of the dynamics of fragmentation/fracture in complex fluids will also help guide the development of new theoretical models that can quantitatively predict the mechanical response of complex fluids in such flows. Two distinct classes of model fluids/gels are studied in this thesis. First, a series of model viscoelastic solutions composed of a flexible homopolymer, poly(ethylene oxide) or PEO, dissolved in a water/glycerol mixture. These dilute solutions are known to behave very similarly to their Newtonian solvent in shearing deformations but exhibit markedly different extensional rheological properties due to the onset of a coil-stretch transition in the solvated microstructure at high elongation rates. Secondly we also consider a family of biopolymer networks: acid-induced casein gels. These canonical protein gels display a multiscale microstructure that is responsible for their gel-like viscoelastic properties. Upon external deformation, these soft viscoelastic solids exhibit a generic power-law rheological response followed by pronounced stress- or strain-stiffening prior to irreversible damage and failure, most often through macroscopic fractures. We study the dynamics of fragmentation for the dilute PEO solutions in different canonical flows: air-assisted atomization, drop impact on a small target, jet impact atomization and rotary spraying. We also study the fracture of the casein protein gels under conditions of both constant applied stress and constant applied shear rate. Through quantitative study of these high strain and high deformation rate phenomena, we reach several conclusions about how the rheological properties of these materials can affect their mechanical behavior in fragmentation/fracture. First, for dilute viscoelastic solutions, the breakup and atomization of these fluids is markedly different than the analogous processes in a simple Newtonian fluid. The average droplet diameter shows a monotonic increase with added viscoelasticity, which is precisely monitored by accurate measurements of elongational relaxation times through a novel characterization method we have developed; Rayleigh Ohnesorge Jet Elongational Rheometry (ROJER). Based on our measurements of the material relaxation time scale a new theoretical model for the evolution in the average droplet diameter is developed for viscoelastic sprays. Second, the size distributions measured in each viscoelastic fragmentation process show a systematic broadening from the Newtonian solvent. In each case the droplet sizes are well described by Gamma distributions that correspond to an underlying fragmentation/coalescence scenario. We show that this broadening results from the pronounced change in the corrugated shape of viscoelastic ligaments as they separate from the liquid core. These corrugations saturate in amplitude and the measured distributions for viscoelastic liquids in each process are given by a universal probability density function, corresponding to a Gamma distribution with nmin = 4. The breadth of this size distribution for viscoelastic filaments is shown to be constrained by a geometrical limit, which can not be exceeded in ligament-mediated fragmentation phenomena. Third, in the fracture of the model acid-induced protein gels, we show that the fractal network of the underlying microstructure leads to a very broad power-law behavior in their linear viscoelastic response that can be precisely modeled by a simple model based on fractional calculus. We show that specific geometric properties of the microstructure set the value of the parameters that are used in the fractional model. The nonlinear viscoelastic properties of the gel can be described in terms of a 'damping function' that enables quantitative prediction of the gel mechanical response up to the onset of macroscopic failure. Using a nonlinear integral constitutive equation - built upon the experimentally-measured damping function in conjunction with power-law linear viscoelastic response - we derive the form of the stress growth in the gel following the start up of steady shear. We also couple the shear stress response with Bailey's durability criteria for brittle solids in order to predict the critical values of the stress and strain for failure of the gel, and show how they scale with the applied shear rate. This provides a generalized failure criterion for biopolymer gels across a range of different deformation histories. Results from this work are of relevance to many processes that involve breakup and rupture of complex fluids such as failure of viscoelastic gels, emulsification, spray painting and even biological processes such as pathogen transfer resulting from violent expiration. By investigating the linear and nonlinear behavior of two distinct classes of soft matter that lie on two ends of the viscoelasticity spectrum, one close to Newtonian liquids and one close to elastic solids, we provide key physical insights that can be generalized to broad classes of different complex fluids that undergo fracture and fragmentation processes.
Author: Paul Manneville
Publisher: Imperial College Press
ISBN: 9781860944918
Category : Science
Languages : en
Pages : 410
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Book Description
This book is an introduction to the application of nonlinear dynamics to problems of stability, chaos and turbulence arising in continuous media and their connection to dynamical systems. With an emphasis on the understanding of basic concepts, it should be of interest to nearly any science-oriented undergraduate and potentially to anyone who wants to learn about recent advances in the field of applied nonlinear dynamics. Technicalities are, however, not completely avoided. They are instead explained as simply as possible using heuristic arguments and specific worked examples.
Author: Saverio E. Spagnolie
Publisher: Springer
ISBN: 1493920650
Category : Science
Languages : en
Pages : 449
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Book Description
This book serves as an introduction to the continuum mechanics and mathematical modeling of complex fluids in living systems. The form and function of living systems are intimately tied to the nature of surrounding fluid environments, which commonly exhibit nonlinear and history dependent responses to forces and displacements. With ever-increasing capabilities in the visualization and manipulation of biological systems, research on the fundamental phenomena, models, measurements, and analysis of complex fluids has taken a number of exciting directions. In this book, many of the world’s foremost experts explore key topics such as: Macro- and micro-rheological techniques for measuring the material properties of complex biofluids and the subtleties of data interpretation Experimental observations and rheology of complex biological materials, including mucus, cell membranes, the cytoskeleton, and blood The motility of microorganisms in complex fluids and the dynamics of active suspensions Challenges and solutions in the numerical simulation of biologically relevant complex fluid flows This volume will be accessible to advanced undergraduate and beginning graduate students in engineering, mathematics, biology, and the physical sciences, but will appeal to anyone interested in the intricate and beautiful nature of complex fluids in the context of living systems.
Author: M J Adams
Publisher: World Scientific
ISBN: 1783263539
Category :
Languages : en
Pages : 513
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Book Description
This volume records the presentations and discussions at the Second Royal Society-Unilever Indo-UK Forum on 'Dynamics of Complex Fluids' which was the culmination of the six-month programme on this topic organised at the Issac Newton Institute for Mathematical Sciences, Cambridge University.The authors of this important volume present an up-to-date, wide-ranging view on developments in the analysis of complex fluid behaviour. Emphasis is placed upon the relation between small-scale structure and large-scale response: this brings together the approaches of molecular physics and continuum mechanics.Experiments, constitutive models and computer simulations are combined to yield new insights into the flow behaviour of polymer melts and solutions, colloidal and neutral particle suspensions, and pastes and soils.
Author: Pengtao Yue
Publisher: MDPI
ISBN: 3039282964
Category : Technology & Engineering
Languages : en
Pages : 142
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Book Description
The presence of drops, bubbles, and particles affects the behavior and response of complex multiphase fluids. In many applications, these complex fluids have more than one non-Newtonian component, e.g., polymer melts, liquid crystals, and blood plasma. In fact, most fluids exhibit non-Newtonian behaviors, such as yield stress, viscoelastity, viscoplasticity, shear thinning, or shear thickening, under certain flow conditions. Even in the complex fluids composed of Newtonian components, the coupling between different components and the evolution of internal boundaries often lead to a complex rheology. Thus the dynamics of drops, bubbles, and particles in both Newtonian fluids and non-Newtonian fluids are crucial to the understanding of the macroscopic behavior of complex fluids. This Special Issue aims to gather a wide variety of papers that focus on drop, bubble and particle dynamics in complex fluids. Potential topics include, but are not limited to, drop deformation, rising drops, pair-wise drop interactions, drop migration in channel flows, and the interaction of particles with flow systems such as pastes and slurries, glasses, suspensions, and emulsions. We emphasize numerical simulations, but also welcome experimental and theoretical contributions.
Author: Akira Onuki
Publisher: Springer Science & Business Media
ISBN: 3642760082
Category : Science
Languages : en
Pages : 231
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Book Description
The fourth Nishinomiya-Yukawa Memorial Symposium, devoted to the topic of dynamics and patterns in complex fluids, was held on October 26 and 27, 1989, in Nishinomiya City, Japan, where ten invited speakers gave their lectures. A one-day meeting, comprising short talks and poster sessions, was then held on the same topic on October 28 at the Research Institute for Fundamental Physics, Kyoto University. The present volume contains the 10 invited papers and 38 contributed papers presented at these two meetings. The symposium was sponsored by Nishinomiya City, where Prof. Hideki Yukawa once lived and where he wrote the celebrated paper describing the work that was later honored by a Nobel prize. The topic of the fourth symposium was chosen from one of the most vigorously evolving and highly interdisciplinary fields in condensed matter physics. The field of complex fluids is very diverse and still in its infancy and, as a result, the definition of a complex fluid varies greatly from one researcher to the next. One of the objectives of the symposium was to clarify its definition by explicitly posing a number of potentially rich problems waiting to be explored. Indeed, experimentalists are disclosing a variety of intriguing dynamical phenomena in complex systems such as polymers, liquid crystals, gels, colloids, and surfactant systems. We, the organizers, hope that the symposium will contribute to the increasing importance of the field in the coming years.
Author: Pengtao Yue
Publisher:
ISBN: 9783039282975
Category : Engineering (General). Civil engineering (General)
Languages : en
Pages : 142
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Book Description
The presence of drops, bubbles, and particles affects the behavior and response of complex multiphase fluids. In many applications, these complex fluids have more than one non-Newtonian component, e.g., polymer melts, liquid crystals, and blood plasma. In fact, most fluids exhibit non-Newtonian behaviors, such as yield stress, viscoelastity, viscoplasticity, shear thinning, or shear thickening, under certain flow conditions. Even in the complex fluids composed of Newtonian components, the coupling between different components and the evolution of internal boundaries often lead to a complex rheology. Thus the dynamics of drops, bubbles, and particles in both Newtonian fluids and non-Newtonian fluids are crucial to the understanding of the macroscopic behavior of complex fluids. This Special Issue aims to gather a wide variety of papers that focus on drop, bubble and particle dynamics in complex fluids. Potential topics include, but are not limited to, drop deformation, rising drops, pair-wise drop interactions, drop migration in channel flows, and the interaction of particles with flow systems such as pastes and slurries, glasses, suspensions, and emulsions. We emphasize numerical simulations, but also welcome experimental and theoretical contributions.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Bhimsen K. Shivamoggi
Publisher: Springer
ISBN: 9789401777117
Category : Technology & Engineering
Languages : en
Pages : 0
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Book Description
This book starts with a discussion of nonlinear ordinary differential equations, bifurcation theory and Hamiltonian dynamics. It then embarks on a systematic discussion of the traditional topics of modern nonlinear dynamics -- integrable systems, Poincaré maps, chaos, fractals and strange attractors. The Baker’s transformation, the logistic map and Lorenz system are discussed in detail in view of their central place in the subject. There is a detailed discussion of solitons centered around the Korteweg-deVries equation in view of its central place in integrable systems. Then, there is a discussion of the Painlevé property of nonlinear differential equations which seems to provide a test of integrability. Finally, there is a detailed discussion of the application of fractals and multi-fractals to fully-developed turbulence -- a problem whose understanding has been considerably enriched by the application of the concepts and methods of modern nonlinear dynamics. On the application side, there is a special emphasis on some aspects of fluid dynamics and plasma physics reflecting the author’s involvement in these areas of physics. A few exercises have been provided that range from simple applications to occasional considerable extension of the theory. Finally, the list of references given at the end of the book contains primarily books and papers used in developing the lecture material this volume is based on. This book has grown out of the author’s lecture notes for an interdisciplinary graduate-level course on nonlinear dynamics. The basic concepts, language and results of nonlinear dynamical systems are described in a clear and coherent way. In order to allow for an interdisciplinary readership, an informal style has been adopted and the mathematical formalism has been kept to a minimum. This book is addressed to first-year graduate students in applied mathematics, physics, and engineering, and is useful also to any theoretically inclined researcher in the physical sciences and engineering. This second edition constitutes an extensive rewrite of the text involving refinement and enhancement of the clarity and precision, updating and amplification of several sections, addition of new material like theory of nonlinear differential equations, solitons, Lagrangian chaos in fluids, and critical phenomena perspectives on the fluid turbulence problem and many new exercises.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 702
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Book Description
