Download or read book Multiscale Investigation of Fundamental Rheological Phenomena in Particulate Suspensions Based on Flow microstructure Interactions written by P. Masafu Mwasame and published by . This book was released on 2018 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: Suspensions and dispersions are an important class of complex fluids frequently encountered in a variety of industrial processes and are prominent in many consumer products such as beauty creams and food dressing. The extensive use of suspensions can be partly attributed to their unique rheological properties such as shear-induced normal stresses, yield stress, time-dependent viscosity and shear thinning. These rheological properties are a direct result of the interplay between the suspension microstructure and flow and have consequences for material processing. The quantitative understanding of suspension rheology so far has been dominated by empirical models. However, such models are either very specialized to particular flows, involve numerous/unphysical parameters, or are inadequate to describe rheological phenomena such as normal stresses. Alternatively, microscopic approaches have primarily been successful in addressing idealized cases and/or small length/time scales. Therefore, the goal of this thesis is to develop new and improved classes of continuum models that clearly connect the suspension microstructure under flow to the observed macroscopic rheology. ☐ In this thesis, new, generally multiscale methods are applied towards developing robust constitutive models for suspension rheology. Two primary modeling approaches are employed to advance the modeling of suspension rheology in this thesis. First is a bottom-up approach that starts from a microscopic description of the suspension microstructure (e.g., the evolving aggregate size distribution) that is then coupled to an empirical/phenomenological equation to allow for the evaluation of the shear stress. The shortcoming of using a phenomenological stress expression is counterbalanced by the accurate microstructure picture provided by a microscopic framework. The second technique is a top-down approach that starts from a macroscopic description of the system through the use of state variables whose dynamic equations are developed within the Hamiltonian-enhanced Non-Equilibrium Thermodynamics framework. The key benefit of this latter approach is that the expressions for the stress tensor and microstructure, with the latter represented by a second rank tensor, emerge self-consistently from the framework. Moreover, the generated equations are applicable to general flows. The multiscale nature of suspension microstructure implies that depending on the phenomena of interest, one or the other or a combination of the two approaches may be favored. Regardless of the approach taken, a recurrent theme in this work is the clear association of the observed macroscopic rheological behavior with an underlying microscopic picture. Finally, for all the suspensions emphasized in this thesis i.e., thixotropic, polydisperse, noncolloidal and emulsions, the corresponding rheological models developed are validated against experimental/simulation data revealing their predictive capability. ☐ A number of important specific accomplishments are achieved in this thesis. To begin with, a population balance-based constitutive model for thixotropic suspensions is developed. Unlike alternative phenomenological models currently in use, a population balance-based model incorporates parameters with clear physical meaning. As a result, the resultant model holds promise for inverse design of thixotropic materials such as pastes that are used in many industrial processes. Next, the use of a conformation tensor as an internal variable to represent changes in suspension microstructure during material deformation is also demonstrated. For the first time, a comprehensive conformation tensor-based framework for suspensions, with a rigor approaching that performed previously for polymeric system, is realized. When applied to dilute emulsions, the conformation tensor-based rheological model that results is in exact agreement with existing asymptotic microscopic theory. In the same emulsion system, effects of microinertia and Ostwald ripening have also been included within a conformation tensor-based model for the first time. In concentrated suspensions, the conformation based theory has been shown to be capable of describing emerging secondary structure in the particle configuration leading to first and second normal stress differences that are both negative. Additional advances have also been made to develop self-consistent approximations for polydisperse suspension viscosity and testing them against prototype experiments. On a broader level, this work provides a number of methodologies for systematic constitutive model development in complex fluids. From an engineering perspective, the results of this thesis can be used to improve upon existing numerical tools, e.g., computational fluid dynamics, to allow for accurate simulation of industrial processes such as extrusion and screen printing of thixotropic pastes, suspensions and emulsions.

Download or read book Particulate Two phase Flow written by M. C. Roco and published by Butterworth-Heinemann. This book was released on 1993 with total page 1032 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a collection of 28 contributions on basic phenomena and advanced methods of investigation for particulate two-phase flow. Written by leading scientists in the field, this book covers new measurement methods, experimental results on particulate two-phase flow microstructure at low and large Reynolds numbers, micromechanical, probabilistic, and numerical simulations, as well as production of ultrafine particles via aerosols and colloids for materials with controlled microstructure. Each chapter is focused on the qualitative progress made in the field in the last several years and has an extensive review section and original results. This unique volume assembles information previously found only in journals and specialized publications. It is an invaluable reference for researchers and engineers from academia and industry.

Download or read book Dilute Non Newtonian Particle Suspension Rheology and Microstructure written by Eric F. Lee and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of polymeric particle suspensions has been the subject of a number of past experimental and theoretical studies. However, fundamental questions about suspension rheology and shear flow-induced microstructural effects remain. First, a quasi-analytical study is presented that gives the first theory-based predictions on the effects of finite polymer relaxation time on rheological properties. In a constant viscosity, low polymer concentration fluid, the addition of particles is found to have a strong shear thickening effect on the first normal stress difference coefficient and the shear viscosity. In contrast, the second normal stress difference coefficient is shear thickening at low shear but shear thinning at higher shear. Next, an analytical and computational study is presented that sheds light on the widely studied phenomenon of cross-streamline particle migration in Poiseuille flow. Particles are found to experience a cross-stream force toward the channel center when they are freely suspended in the fluid, while they experience a crossstream force toward the wall when they are fixed in place.

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 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential text on practical application, theory and simulation, written by an international coalition of experts in the field and edited by the authors of Colloidal Suspension Rheology. This up-to-date work builds upon the prior work as a valuable guide to formulation and processing, as well as fundamental rheology of colloidal suspensions. Thematically, theory and simulation are connected to industrial application by consideration of colloidal interactions, particle properties, and suspension microstructure. Important classes of model suspensions including gels, glasses and soft particles are covered so as to develop a deeper understanding of industrial systems ranging from carbon black slurries, paints and coatings, asphalt, cement, and mine tailings, to natural suspensions such as biocolloids, protein solutions, and blood. Systematically presenting the established facts in this multidisciplinary field, this book is the perfect aid for academic researchers, graduate students, and industrial practitioners alike.

Download or read book Flow and Microstructure of Dense Suspensions Volume 289 written by Leslie J. Struble and published by . This book was released on 1993-05-28 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.

Download or read book Rheological Phenomena in Focus written by D.V. Boger and published by Elsevier Science & Technology. This book was released on 1993-07-23 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The text also deals with confined, oscillating and rotatory flow.

Download or read book The Rheology of Attractive Suspensions written by Derek Eusean Huang and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex fluids form a broad class of materials, examples of which include foodstuffs, personal care products, biological fluids, industrial compounds, and geological materials. Detailed knowledge of their flow behavior is therefore key to understanding and predicting natural phenomena or developing new materials. In the past century, major advances in both experimental and theoretical methods have enabled greater understanding of the connection between the microscopic physical structure of complex fluids and their material response. Traditional rheology involves imposing deformation on a macroscopic sample of fluid and measuring the stress response. However, an increasing need to interrogate microscopically-small fluid samples, and a heightened interest in the colloid-level physics of biology, have motivated the development of techniques to interrogate microliter-size samples and resolve micron-length heterogeneities. One of these experimental techniques is active microrheology, where a microscopically small probe particle is driven through the material of interest. Constitutive relations between the force required to drive the probe and the speed with which it moves allow one to infer the effective viscosity of the material, and more recent expansions of the theory of active microrheology allow the direct measurement of suspension stress by monitoring the mean and fluctuating motion of the probe. Theoretical models that connect probe motion to material and flow properties have enjoyed great expansion in the last decade for the study of complex fluids of particles interacting hydrodynamically, or with repulsive forces. However, many systems of interest, including biological cells, comprise colloidal suspensions that experience attractive forces not previously represented in theoretical models. This work presents a theoretical study of the impact of attractive forces on the microstructure, microviscosity, and nonequilibrium osmotic pressure of colloidal suspensions as measured by active microrheology. In active microrheology, the probe distorts the surrounding microstructure from its equilibrium configuration. The degree of this distortion is set by the strength of external forcing relative to entropic restoring forces; interparticle attractions and repulsions also influence this evolution. Although the effects of repulsions are well-studied in prior literature, a theoretical understanding of attraction-induced effects on nonequilibrium rheology is lacking. To examine how this interplay between different microscopic forces influences rheology, we formulate a Smoluchowski equation governing pair configuration as it evolves with flow strength, interparticle attractions, and hydrodynamic interactions. We determine its solution and compute microviscosity and nonequilibrium osmotic pressure from the structure via statistical mechanics. When the probe is subject to external forcing, attractions speed upstream probe-bath encounters and slow downstream detachment, transferring particle density downstream. This sets both the strength and direction of dipolar disturbance under weak forcing and the boundary-layer and wake structure under strong forcing. These attraction-induced structural changes affect rheology: both attraction-thinning and attraction-thickening are observed in the weak-forcing limit, while sufficiently strong forcing breaks attractive bonds and leads to flow-thinning or, in the presence of hydrodynamic interactions, flow-thickening. We find that the equilibrium osmotic pressure, described by the second virial coefficient B2, accurately predicts structural and rheological behavior in the weak-forcing limit regardless of specific attractive potential, but that the secondary length scale that arises under strong forcing precludes potential-agnostic observations far from equilibrium. The structural transitions and non-monotonic rheology in active microrheology show that tuning surface stickiness can either enhance or hinder probe motion and provide a means by which proteins or other macromolecules may change their surface chemistry to alter the viscosity of the surrounding medium, either speeding or slowing their own motion. Attractive forces are known to reduce the equilibrium osmotic pressure; as the second virial coefficient becomes more strongly negative, it is possible for phase separation to occur. This behavior changes away from equilibrium, where we find that the flow-induced nonequilibrium osmotic pressure reaches a minimum at a critical value of B2 before increasing with attraction strength. Hydrodynamic interactions suppress the nonequilibrium osmotic pressure and, at certain attraction strengths, can give rise to a flow-induced reduction in osmotic pressure below its equilibrium value. This denotes a flow-induced destabilization of attractive suspensions that may lead to phase separation in more concentrated systems, suggesting that self-assembly of active particles in biological suspensions may be driven by both attractive forces and hydrodynamic interactions

Download or read book Rheology and Interparticle Interaction Studies in Complex Media written by Prasad S. Bhosale and published by . This book was released on 2012 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dense colloidal dispersions are rheologically complex and exhibit properties like yield stress, creep, and elasticity due to aggregation and other interparticle interactions. The overall rheological performance of the system is due to the multiscale properties and mechanics: the nanoscale interactions between particles determine the microscopic texture, i.e. aggregate compactness, structure and strength. At microscale the micromechanics and microstructure evolution in aggregates under stress define the macroscale rheological performance. The interparticle forces and microstructure also evolve over time (aging interparticle bonds and aggregate structures), leading to time/frequency dependent rheological behavior. The systems of specific interest here are dense nuclear waste slurries stored at the US Department of Energy sites at Hanford, WA and Savannah, GA since 1943. Rheological modifiers are currently being investigated for effective transport of these dense waste slurries in the vitrification process developed for more permanent radioactive waste disposal. The overall objective of the study is to fundamentally understand the performance of rheology modifiers in environments similar to those of nuclear waste slurries. We are particularly focused on the effect of rheology modifiers on interparticle interactions and its implication towards bulk rheological performance. These interactions were investigated through various macroscale (rheology and electroacoustics) and microscale (atomic force microscope) colloidal interaction measurement techniques. The implications of these interactions towards rheological performance are studied using the simple yield stress model defined by Russel et al. Here the model has been extended to steric, and bridging forces between particles. It was identified that polyelectrolytes, specifically poly (acrylic acid), is an effective rheology modifier for high pH and high salt content environments of nuclear waste slurries. The correct choice of molecular weight of the PAA was especially important to its effectiveness: too low a value provides insufficient steric stabilization, while too high a value induces bridging. The effect of poly (acrylic acid) adsorption on the electrokinetic behavior of alumina dispersions under high pH conditions was also investigated as a function of polymer concentration and molecular weight as well as the presence, concentration and ion type of background electrolyte. The interparticle interaction forces were directly measured in nuclear waste simulant using atomic force microscopy. A link between the dynamics of polymer bridging and disruption and bulk rheology was established for a model dense colloidal suspension of silica particles flocculated by polyethylene oxide (PEO). In the finial study, as a side project, we have expanded acoustic spectroscopy and electroacoustic techniques to characterize particles dispersed in viscoelastic polymer gel media (another complex system of interest).

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 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 Complex Fluids in Biological Systems written by Saverio E. Spagnolie and published by Springer. This book was released on 2014-11-27 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

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 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.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 862 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Colloids and the Depletion Interaction written by Henk N.W. Lekkerkerker and published by Springer Science & Business Media. This book was released on 2011-05-12 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloids are submicron particles that are ubiquitous in nature (milk, clay, blood) and industrial products (paints, drilling fluids, food). In recent decades it has become clear that adding depletants such as polymers or small colloids to colloidal dispersions allows one to tune the interactions between the colloids and in this way control the stability, structure and rheological properties of colloidal dispersions. This book offers a concise introduction to the fundamentals of depletion effects and their influence on the phase behavior of colloidal dispersions. Throughout the book, conceptual explanations are accompanied by experimental and computer simulation results. From the review by Kurt Binder: "They have succeeded in writing a monograph that is a very well balanced compromise between a very pedagogic introduction, suitable for students and other newcomers, and reviews of the advanced research trends in the field. Thus each chapter contains many and up to date references, but in the initial sections of the chapters, there are suggested exercises which will help the interested reader to recapitulate the main points of the treatment and to deepen his understanding of the subject. Only elementary knowledge of statistical thermodynamics is needed as a background for understanding the derivations presented in this book; thus this text is suitable also for advanced teaching purposes, useful of courses which deal with the physics for soft condensed matter. There does not yet exist any other book with a similar scope..... The readability of this book is furthermore enhanced by a list of symbols, and index of keywords, and last not least by a large number of figures, including many pedagogic sketches which were specifically prepared for this book. Thus, this book promises to be very useful for students and related applied sciences alike." Eur. Phys. J. E (2015) 38: 73

Download or read book Flowing Matter written by Federico Toschi and published by Springer Nature. This book was released on 2019-09-25 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book, published in the Soft and Biological Matter series, presents an introduction to selected research topics in the broad field of flowing matter, including the dynamics of fluids with a complex internal structure -from nematic fluids to soft glasses- as well as active matter and turbulent phenomena. Flowing matter is a subject at the crossroads between physics, mathematics, chemistry, engineering, biology and earth sciences, and relies on a multidisciplinary approach to describe the emergence of the macroscopic behaviours in a system from the coordinated dynamics of its microscopic constituents. Depending on the microscopic interactions, an assembly of molecules or of mesoscopic particles can flow like a simple Newtonian fluid, deform elastically like a solid or behave in a complex manner. When the internal constituents are active, as for biological entities, one generally observes complex large-scale collective motions. Phenomenology is further complicated by the invariable tendency of fluids to display chaos at the large scales or when stirred strongly enough. This volume presents several research topics that address these phenomena encompassing the traditional micro-, meso-, and macro-scales descriptions, and contributes to our understanding of the fundamentals of flowing matter. This book is the legacy of the COST Action MP1305 “Flowing Matter”.

Download or read book Mobile Particulate Systems written by E. Guazzelli and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mobile particulate systems involve the mechanics, flow and transport properties of mixtures of fluids and solids. These systems are intrinsic to the rheology of emulsions and suspensions, flocculation and aggregation, sedimentation and fluidization, flow of granular media, nucleation and growth of small particles, segregation, attrition and solidification processes. Its diversity means that the area has been studied by a number of different disciplines (e.g. chemical or civil engineering, mechanics, hydrodynamics, geophysics, condensed matter and statistical physics, etc.). Mobile Particulate Systems features general, orientational lectures and advanced topics, covering state of the art approaches to the study of suspensions, fluidized beds, sedimentation and granular flows.