Download or read book Time resolved Linear and Non linear Rheology of Thixotropic and Aging Complex Fluids written by Joshua David John Rathinaraj and published by . This book was released on 2021 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Temporal changes in microstructure and relaxation dynamics are ubiquitously observed in materials such as hydrogels, food products and drilling fluids. These materials are in general known as mutating materials and the build-up or breakdown of microstructure is commonly both time- and shear-rate (or shear-stress)-dependent resulting in a range of complex phenomena collected under the term thixotropy. It is becoming increasingly im- portant to develop time-resolved rheometric techniques to quantify the behavior of mutating materials accurately. In the present study we first discuss the introduction of better time-resolved techniques in superposition rheometry. Conventional superposition rheometry consists of combining Small Amplitude Oscillatory Shear (SAOS) with a steady unidirectional shear rate to gain insight into the shear-induced changes to the viscoelastic properties of a complex fluid. Orthogonal superposition (OSP), in which the two modes of deformation are perpendicular, has been preferred over parallel superposition to avoid non-linear cross-coupling of the steady shear and oscillatory deformation fields. This cross coupling can lead to unphysi- cal sign changes in the measured material properties, and makes it difficult to interpret the flow-induced mechanical properties. Recently, orthogonal superposition has been used to investigate the shear-induced anisotropy taking place in colloidal gels by comparing the transient evolution of orthogonal moduli with the parallel moduli immediately after cessa- tion of shear. However, probing transient evolution using the OSP technique can be chal- lenging for rapidly mutating complex materials which evolve on time scales comparable to the time scale of the experiment. Using a weakly associated alginate gel, we demonstrate the potential of superimposing fast optimally windowed chirp (OWCh) deformations or- thogonally to the shear deformation which substantially reduces the measurement time. We evaluate the changes in the rate-dependent relaxation spectrum in the direction of applied unidirectional shear rate and in the orthogonal direction deduced from the damping function and orthogonal moduli data respectively. We measure systematic changes between the two spectra measured in orthogonal directions thus revealing and quantifying flow-induced anisotropy in the alginate gel. Secondly, we develop a signal processing technique to monitor accurate temporal evolution of the complex modulus for a specified deformation frequency. Oscillatory rheometric techniques such as Small Amplitude Oscillatory Shear (SAOS) and, more recently, Large Amplitude Oscillatory Shear (LAOS) are now quite widely used for rheological characterization of the viscoelastic properties of complex fluids. However, the conventional application of Fourier transforms for analyzing oscillatory data assume the signals are time- translation invariant, which constrains the rate of mutation of the material to be extremely small. This constraint makes it difficult to accurately study shear-induced microstructural changes in thixotropic and gelling materials. We explore applications of the Gabor transform (a Short Time Fourier Transform (STFT) combined with a Gaussian window), for providing optimal joint time-frequency resolution of a mutating material's viscoelastic properties. First, we show using simple analytic models that application of the STFT enables extraction of useful data from the initial transient response following the inception of oscillatory flow. Secondly, using measurements on a Bentonite clay we show that using a Gabor transform enables us to more accurately measure rapid changes in both the storage and loss modulus with time, and also extract a characteristic thixotropic/aging time scale for the material. Finally, we consider extension of the Gabor transform to non-linear oscillatory deformations using an amplitude-modulated input strain signal, in order to track the evolution of the Fourier-Chebyshev coefficients characterizing thixotropic fluids at a specified deformation frequency. We show that there is a trade-off between frequency and time resolution (effectively a rheological uncertainty principle). We refer to the resulting test proto col as Gaborheometry and construct an operability diagram in terms of the imposed ramp rate and the mutation time of the material. This unconventional, but easily implemented, rheometric approach facilitates both SAOS and LAOS studies of time-evolving materials, reducing the number of required experiments and the data post-processing time significantly. Finally, we use the time-resolved techniques developed in this thesis to understand the thixotropic aging behavior of bentonite dispersions. In soft glassy materials such as ben- tonite clays, the relaxation dynamics and the microstructure slowly but continuously evolve with time to progressively form more stable structures. We investigate and quantify this complex aging behavior of bentonite dispersions by measuring the evolution in the linear viscoelastic behavior at different age times and temperatures. We model the linear viscoelastic properties using a material time domain transformation and a fractional Maxwell gel model which allows us to develop a rheological master curve to quantify and predict the aging behavior of this soft glass over a range of temperatures and time scales. The time-resolved rheometric techniques and procedures for quantifying the rheology of rapidly mutating complex fluids can be extended to a wide range of soft materials and allows us to obtain insight into how microstructural changes drive the evolution in the bulk rheological behavior for thixotropic and aging materials.

Download or read book Rheology of Complex Fluids written by Abhijit P. Deshpande and published by Springer Science & Business Media. This book was released on 2010-09-20 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the School on Rheology of Complex fluids is to bring together young researchers and teachers from educational and R&D institutions, and expose them to the basic concepts and research techniques used in the study of rheological behavior of complex fluids. The lectures will be delivered by well-recognized experts. The book contents will be based on the lecture notes of the school.

Download or read book The Linear and Nonlinear Rheology of Multiscale Complex Fluids written by Aditya Jaishankar and published by . This book was released on 2014 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: The microstructures of many complex fluids are typically characterized by a broad distribution of internal length scales. Examples of such multiscale materials include physically and chemically cross-linked gels, emulsions, soft colloidal glasses and concentrated suspensions. Due to the complex microstructure, these materials exhibit multiscale power law relaxation under externally imposed deformation. Compact constitutive frameworks that can accurately describe and predict both the linear as well as the nonlinear rheology of such complex fluids have remained elusive. Moreover, the rheological behavior of these materials under extensional deformations, which is important in applications such as spraying and fiber spinning, is relatively poorly understood. The primary contribution of this thesis is the development of a compact constitutive modeling framework to quantitatively describe the rheology of multiscale complex fluids. In the linear limit of small deformations, fractional constitutive equations in conjunction with the concept of quasi-properties have been shown to provide accurate physical descriptions of the broad power law relaxation dynamics exhibited by multiscale materials. In this thesis we very generally show how fractional constitutive equations enable the prediction of the rheological response of multiscale fluids under complex deformation profiles. As a specific example, we analyze the damped inertio-elastic oscillations exhibited at early times by viscoelastic interfacial layers upon the imposition of a constant stress, and the subsequent long time power law creep. We also analyze the small strain lubrication flow regime of a typical tack experiment performed on a crosslinked power law gel, where the extensional deformation of the complex material plays an important role. We extend these models to the large strain nonlinear regime using an integral K-BKZ framework coupled with a strain damping function. We demonstrate in a general manner that nonlinear rheological responses such as shear-thinning and positive first normal stress coefficients can be predicted a priori from linear viscoelastic data and a single additional nonlinear parameter introduced through the damping function. We also demonstrate that well-known empirical rheological models utilized to describe nonlinear behavior such as the Herschel-Bulkley, Cross and Carreau models can be derived using the K-BKZ framework by selecting a suitable fractional relaxation kernel and an appropriate damping function. Additionally, we derive expressions for linear viscometric functions as well as the first normal stress coefficient for materials that exhibit steady shear flow behavior predicted by the above empirical models. Our approach also quantifies the applicability of widely known empirical rheological rules for nonlinear rheology such as the Cox-Merz rule. The second contribution of this thesis is in increasing the understanding of the rheological behavior of multiscale complex fluids in extensional flow fields. For this purpose we utilize a variety of experimental extensional rheology techniques such as Capillary Breakup Extensional Rheometry (CaBER), Filament Stretching Extensional Rheometry (FiSER) and an Optimized Shape Cross-slot Extensional Rheometer (OSCER). Due to their ubiquity in industrial applications as well as in biologically relevant complex fluids, we primarily study aqueous polysaccharide systems (for example Mamaku gum). With the help of these detailed experiments, we investigate and quantify the strength of hydrogen-bonding interactions in this multiscale physically associated gel. We also investigate the extensional rheology of Hyaluronic acid, which has been shown to be an important factor in proper synovial fluid function. The findings of this thesis are widely applicable given the widespread use of multiscale complex fluids in industrial, and biological applications. The fractional constitutive framework derived here overcomes the limitations of current modeling approaches that invoke a large number of empirical constitutive parameters. Our simple models will be useful for quantitative material diagnostics and quality control comparisons as well as for computational simulations. Moreover, the experimental findings on the extensional rheology of multiscale polysaccharide systems will help in the formulation of biologically relevant complex fluids for the treatment of physiological conditions such as osteoarthritis and dysphagia.

Download or read book Role of Viscoelasticity and Non linear Rheology in Flows of Complex Fluids at High Deformation Rates written by Thomas Joseph Ober and published by . This book was released on 2013 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: We combine pressure, velocimetry and birefringence measurements to study three phenomena for which the fluid rheology plays a dominant role: 1) shear banding in micellar fluids, 2) extension-dominated flows in microfluidic devices, and 3) flow-induced particle migration in microchannels. Firstly, worm-like micellar solutions are model non-Newtonian fluids having a single relaxation time [beta]. At shear rates larger than ... however, these systems exhibit shear banding and non-linear rheological behavior, whose importance is characterized by the Weissenberg number ... We develop a stability criterion for the onset of a purely viscoelastic instability for shear-banding fluids, to establish the limitations of conventional rheometric techniques for studying these fluids. A second challenge for conventional rheometers is inertially-driven secondary flows. The onset of these flows is governed by the Reynolds number ... where U is the velocity, D is the flow geometry length and v is the fluid kinematic viscosity. We develop microfluidic devices to impose shear and extensional deformation rates up to ...at low Re. These experiments combine pressure measurements, micro-particle image velocimetry ([mu]-PIV) and birefringence measurements. We develop a microfluidic chip that enables applied rheologists to quantitatively differentiate between fluid formulations intended for applications at high deformation rates. Finally, we study the interplay between fluid inertia and elasticity on particle migration. The inertially-dominated case is governed by the channel Reynolds number Re, and particle Reynolds number ... where a is the particle diameter. In a microfluidic device, the particle and channel size are on the same order, and hence migration occurs at ... in the so-called 'inertial focusing' regime which may have applications in clinical medicine. However, most physiological fluids are viscoelastic and therefore particle migration in these fluids occurs at high Reynolds and Weissenberg numbers, which is a mostly unstudied regime. We combine pressure measurements, streak imaging, [my]-PIV and particle trajectory analysis (PTA) to study the migration of polystyrene beads. Inertia drives particles toward the channel walls, whereas elasticity drives particles toward the channel centerline even at Re, ~ 2000.

Download or read book Time resolved Rheology on Complex Fluids written by V. I. Markmann and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nonlinear Rheological Characterization and Modeling of Complex Fluids Under Large Amplitude Oscillatory Shear LAOS written by Christopher Joseph Hershey and published by . This book was released on 2018 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Colloidal Suspension Rheology written by Jan Mewis and published by Cambridge University Press. This book was released on 2012 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented in an accessible and introductory manner, this is the first book devoted to the comprehensive study of colloidal suspensions.

Download or read book Theory and Applications of Colloidal Suspension Rheology written by Norman J. Wagner and published by Cambridge University Press. This book was released on 2021-04-15 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Essential text on the practical application and theory of colloidal suspension rheology, written by an international coalition of experts.

Download or read book Non Newtonian Flow and Applied Rheology written by R. P. Chhabra and published by Elsevier. This book was released on 2011-04-08 with total page 750 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book bridges the gap between the theoretical work of the rheologist, and the practical needs of those who have to design and operate the systems in which these materials are handled or processed. It is an established and important reference for senior level mechanical engineers, chemical and process engineers, as well as any engineer or scientist who needs to study or work with these fluids, including pharmaceutical engineers, mineral processing engineers, medical researchers, water and civil engineers. This new edition covers a considerably broader range of topics than its predecessor, including computational fluid dynamics modelling techniques, liquid/solid flows and applications to areas such as food processing, among others. * Written by two of the world's leading experts, this is the only dedicated non-Newtonian flow reference in print. * Since first publication significant advances have been made in almost all areas covered in this book, which are incorporated in the new edition, including developments in CFD and computational techniques, velocity profiles in pipes, liquid/solid flows and applications to food processing, and new heat/mass transfer methods and models. * Covers both basic rheology and the fluid mechanics of NN fluids ? a truly self-contained reference for anyone studying or working with the processing and handling of fluids

Download or read book Ionic Liquids written by Mark B. Shiflett and published by ACS Symposium. This book was released on 2018-07-02 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this book is to provide an update on some of the latest research and applications in the broad field of ionic liquids. This volume spans research and development activities ranging from fundamental and experimental investigations to commercial applications. A brief history of the field is included, as well as both new developments and reviews organized in the general topical areas of applications, materials, biomass processing, and fundamental studies. This book attempts to propel the field forward by bringing together contributions from some of the foremost researchers on ionic liquids. Recent products and new large-scale processes using ionic liquids, both in operation and being announced, indicate that an exciting new chapter in this field is about to begin. The authors summarize some of the history, applications, conferences, books, databases, issues related to data quality and toxicity for researchers working in the field of ionic liquids and includes an overview for each proceeding chapter with an introduction about the authors.

Download or read book Product Design and Engineering written by Ulrich Bröckel and published by John Wiley & Sons. This book was released on 2013-08-02 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering the whole value chain - from product requirements and properties via process technologies and equipment to real-world applications - this reference represents a comprehensive overview of the topic. The editors and majority of the authors are members of the European Federation of Chemical Engineering, with backgrounds from academia as well as industry. Therefore, this multifaceted area is highlighted from different angles: essential physico-chemical background, latest measurement and prediction techniques, and numerous applications from cosmetic up to food industry. Recommended reading for process, pharma and chemical engineers, chemists in industry, and those working in the pharmaceutical, food, cosmetics, dyes and pigments industries.

Download or read book Binder Characterization and Evaluation written by David A. Anderson and published by Strategic Highway Research Program (Shrp). This book was released on 1994 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computational Rheology written by Robert G. Owens and published by World Scientific Publishing Company. This book was released on 2002 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work traces the development of numerical methods for non-Newtonian flows from the late 1960s to 2001. It begins with broad coverage of non-Newtonian fluids, including their mathematical modelling and analysis, and then specific computational techniques are discussed.

Download or read book Constitutive Equations for Polymer Melts and Solutions written by Ronald G. Larson and published by Butterworth-Heinemann. This book was released on 2013-10-22 with total page 381 pages. Available in PDF, EPUB and Kindle. Book excerpt: Constitutive Equations for Polymer Melts and Solutions presents a description of important constitutive equations for stress and birefringence in polymer melts, as well as in dilute and concentrated solutions of flexible and rigid polymers, and in liquid crystalline materials. The book serves as an introduction and guide to constitutive equations, and to molecular and phenomenological theories of polymer motion and flow. The chapters in the text discuss topics on the flow phenomena commonly associated with viscoelasticity; fundamental elementary models for understanding the rheology of melts, solutions of flexible polymers, and advanced constitutive equations; melts and concentrated solutions of flexible polymer; and the rheological properties of real liquid crystal polymers. Chemical engineers and physicists will find the text very useful.

Download or read book The Rheology Handbook written by Thomas G. Mezger and published by Vincentz Network GmbH & Co KG. This book was released on 2006 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Practical Hydroinformatics written by Robert J. Abrahart and published by Springer Science & Business Media. This book was released on 2008-10-24 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydroinformatics is an emerging subject that is expected to gather speed, momentum and critical mass throughout the forthcoming decades of the 21st century. This book provides a broad account of numerous advances in that field - a rapidly developing discipline covering the application of information and communication technologies, modelling and computational intelligence in aquatic environments. A systematic survey, classified according to the methods used (neural networks, fuzzy logic and evolutionary optimization, in particular) is offered, together with illustrated practical applications for solving various water-related issues. ...

Download or read book Food Oral Processing written by Jianshe Chen and published by John Wiley & Sons. This book was released on 2012-04-16 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides an overview of the latest research findings on the physics, physiology, and psychology of food oral consumption, as well as the experimental techniques available for food oral studies. Coverage includes the main physical and physiological functionalities of the mouth; the location and functionalities of various oral receptors; the main sequences of eating and drinking, and the concomitant food disintegration and destabilisation. Chapters also explain oral processing and its relation to flavour release and texture perception, and there is an introduction to the principles of food rheology as they relate to eating. Food Oral Processing is directed at food scientists and technologists in industry and academia, especially those involved in sensory science and new product development. It will also be of interest to oral physiologists, oral biologists and dentists. The book will be a useful reference for undergraduate and postgraduate students of these disciplines.