Download or read book Dense Colloidal Suspensions in Microchannel Flow written by Philipp Kanehl and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Confined Flow of Attractive Colloidal Suspensions written by Rahul Pandey and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Attractive particulate fluids flowing through complex confined geometries are frequently used in technological applications. While the flow properties of hard-sphere suspensions in micro-scale geometries have been studied extensively, the effects of interparticle attractions and particle size dispersity on the confined flow properties of particulate suspensions are not well understood. We used confocal microscopy, particle tracking, and bulk rheology to study the confined structure, dynamics, and flow properties of colloid-polymer mixtures, which serve as simple models of attractive particulate suspensions. We employed poly(methyl-methacrylate) spheres that were suspended in a refractive-index and density- matched solvent, and induced a controlled short-range depletion attraction between particles by adding non-absorbing linear polystyrene. First, we investigated the effects of particle size dispersity on confinement-induced solidification of colloid-polymer mixtures. We formulated mixtures of polymer and bidispersed colloids with particle size ratio aS/aL ≈ 0.49 at a constant total volume fraction fT and measured the dynamics of the large particles as a function of the volume fraction of large particles. The dynamics of large particles became slower as the volume fraction of large particles r=fL/fT was decreased or the confinement thickness was decreased, indicating increasingly solid-like behavior. Second, we investigated the effects of variation in particle size dispersity r on the rheology and microstructure of mixtures of polymer and bidispersed colloids. Significant changes in rheology and microstructure were observed only at high volume fractions of large particles. By contrast, dense suspensions fT = 0.40 were strong gels at all concentration of large particles and exhibited only modest rheological and microstructural changes. Finally, we investigated the effects of variation in interparticle attractions on the microchannel flow of colloid-polymer mixtures. In suspensions with weak interparticle attractions, the number density of particles increased downstream in the channel due to shear-induced migration and consolidation by compression. In suspensions with stronger interparticle attractions, an interconnected network of particles suppressed these mechanisms and prevented the increase in density downstream. Together, our results indicate that the confined structure, dynamics, and flow properties of attractive colloidal suspensions can be controllably tuned from fluid-like to solid-like by varying the interparticle attractions and the particle size dispersity.

Download or read book Capillary Flow of Dense Colloidal Suspensions written by Lucio Isa and published by . This book was released on 2008 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this thesis is to study the flow of dense colloidal suspensions into micronsized capillaries at the particle level. Understanding the flow of complex fluids in terms of their constituents (colloids, polymers, or surfactants) poses deep fundamental challenges, and has wide applications in many industrial processes. Through the use of a novel experimental procedure we find results contrasting with the predicted bulk rheological behaviour of dense colloidal systems and propose an alternative approach based on the analogy with granular systems. Quantitative predictions which successfully explain the data are obtained. In order to obtain quantitative information on the dynamics of the system, we image the flow using a fast confocal microscope and identify the trajectories of each particle. Due to the nature of the flow, conventional techniques for locating and tracking the particles fail to yield satisfactory results. To overcome this limitation, we have developed a novel technique which allows us to successfully track the particles in strongly non-uniform flow fields (published, 2006). We focus our attention on three main aspects of the flow: concentration gradients, velocity profiles and time behaviour. We initially discuss the occurrence of concentration gradients along the flow direction and relate them to the local flow profiles. We observe high density regions where the velocity is uniform across the channel (complete plugs) and lower density regions where shear is present. The observed concentration profiles can be qualitatively explained by considering the relative ow between the solvent and the suspended particles. The flow profiles in the presence of shear consist of a plug in the centre while shear occurs localized adjacent to the channel walls, reminiscent of yield-stress fluid behaviour. However, the observed scaling of the velocity profiles with the flow rate strongly contrasts yield-stress fluid predictions. Instead, the velocity profiles can be captured by a theory of stress fluctuations originally developed for chute flow of dry granular media (published ,2007). We extend the model to our case and discuss it as a function of a series of parameters (boundary conditions, volume fraction, channel size, etc.) highlighting differences and similarities with granular media. Finally we discuss the time behaviour of complete plug flows relating it to the microscopic dynamics of the particles. At variance with dilute systems, dense systems exhibit velocity fluctuations when driven into channels by a constant pressure difference. We find that there exists a threshold value of the flow rate below which oscillations in the velocity are absent and above which their frequency scales as a power law of the flow rate. Despite quantitative predictions on this issue that are still missing, we present a microscopic description of the phenomenon highlighting the interplay between the particles and the solvent.

Download or read book Electrokinetic and Colloid Transport Phenomena written by Jacob H. Masliyah and published by John Wiley & Sons. This book was released on 2006-05-26 with total page 733 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new, definitive perspective of electrokinetic and colloid transport processes Responding to renewed interest in the subject of electrokinetics, Electrokinetic and Colloid Transport Phenomena is a timely overview of the latest research and applications in this field for both the beginner and the professional. An outgrowth of an earlier text (by coauthor Jacob Masliyah), this self-contained reference provides an up-to-date summary of the literature on electrokinetic and colloid transport phenomena as well as direct pedagogical insight into the development of the subject over the past several decades. A distinct departure from standard colloid science monographs, Electrokinetic and Colloid Transport Phenomena presents the most salient features of the theory in a simple and direct manner, allowing the book to serve as a stepping-stone for further learning and study. In addition, the book uniquely discusses numerical simulation of electrokinetic problems and demonstrates the use of commercial finite element software for solving these multiphysics problems. Among the topics covered are: * Mathematical preliminaries * Colloidal systems * Electrostatics and application of electrostatics * Electric double layer * Electroosmosis and streaming potential * Electrophoresis and sedimentation potential * London-Van der Waals forces and the DLVO theory * Coagulation and colloid deposition * Numerical simulation of electrokinetic phenomena * Applications of electrokinetic phenomena Because this thorough reference does not require advanced mathematical knowledge, it enables a graduate or a senior undergraduate student approaching the subject for the first time to easily interpret the theories. On the other hand, the application of relevant mathematical principles and the worked examples are extremely useful to established researchers and professionals involved in a wide range of areas, including electroosmosis, streaming potential, electrophoretic separations, industrial practices involving colloids and complex fluids, environmental remediation, suspensions, and microfluidic systems.

Download or read book Effect of Attractions on the Flow Properties of Dense Colloidal Suspensions written by Vijay Gopalakrishnan and published by . This book was released on 2004 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Suspensions of Colloidal Particles and Aggregates written by Frank Babick and published by Springer. This book was released on 2016-04-04 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the properties of particles in colloidal suspensions. It has a focus on particle aggregates and the dependency of their physical behaviour on morphological parameters. For this purpose, relevant theories and methodological tools are reviewed and applied to selected examples. The book is divided into four main chapters. The first of them introduces important measurement techniques for the determination of particle size and interfacial properties in colloidal suspensions. A further chapter is devoted to the physico-chemical properties of colloidal particles—highlighting the interfacial phenomena and the corresponding interactions between particles. The book’s central chapter examines the structure-property relations of colloidal aggregates. This comprises concepts to quantify size and structure of aggregates, models and numerical tools for calculating the (light) scattering and hydrodynamic properties of aggregates, and a discussion on van-der-Waals and double layer interactions between aggregates. It is illustrated how such knowledge may significantly enhance the characterisation of colloidal suspensions. The final part of the book refers to the information, ideas and concepts already presented in order to address technical aspects of the preparation of colloidal suspensions—in particular the performance of relevant dispersion techniques and the stability 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 The Flow of Colloidal Suspensions Through Porous Media written by Robert John Hunter and published by . This book was released on 1962 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Towards Designing Flow Mechanics in Dense Suspensions of Smooth and Rough Colloids written by Shravan Pradeep and published by . This book was released on 2021 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure and Diffusion in Dense Confined Colloidal Suspensions written by Bianxiao Cui and published by . This book was released on 2002 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Colloids Grains and Dense Suspensions Under Flow and Under Arrest written by Royal Society (Great Britain) and published by . This book was released on 2009 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Active and Nonlinear Microrheology of Dense Colloidal Suspensions written by Christian Josef Harrer and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow induced Diffusion in Dilute Colloidal Suspensions written by Oleg Victor Bychuk and published by . This book was released on 1996 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nonlinear Microrheology of Dense Colloidal Suspensions written by Igor Gazuz and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microfluidics and BioMEMS Applications written by Francis E. H. Tay and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfluidics and BioMEMS Applications central idea is on microfluidics, a relatively new research field which finds its niche in biomedical devices, especially on lab-on-a-chip and related products. Being the essential component in providing driving fluidic flows, an example of micropump is chosen to illustrate a complete cycle in development of microfluidic devices which include literature review, designing and modelling, fabrication and testing. A few articles are included to demonstrate the idea of tackling this research problem, and they cover the main development scope discussed earlier as well as other advanced modelling schemes for microfluidics and beyond. Scientists and students working in the areas of MEMS and microfluidics will benefit from this book, which may serve both communities as both a reference monograph and a textbook for courses in numerical simulation, and design and development of microfluidic devices.

Download or read book Colloidal Suspension Flow and Transport Behavior in Small Channels by Magnetic Resonance Microscopy written by Jennifer Ruth Brown and published by . This book was released on 2007 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research presented addresses colloidal transport issues in small channel systems using Magnetic Resonance Microscopy techniques. In transport phenomena, the interaction between convection or deterministic motions and diffusion or random motions is important in many engineering and natural applications, especially relating to multiphase flows. Magnetic Resonance methods have the ability to separate coherent from incoherent motion, as well as measure spatially resolved velocity, probability distributions of displacement, and microstructure on the pore scale, even within a multiphase colloidal system. A dilute (f

Download or read book Phase Behavior and Effective Interactions in Colloidal Suspensions written by and published by Cuvillier Verlag. This book was released on 2007-04-25 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Colloidal suspensions describe particles with size from typically a few nanometers to a few microns which are dispersed in a medium. In physics, in chemistry, and in biology colloids play an important role and the study of colloidal systems underwent a recent renaissance. This is based on the development of experimental techniques, the availability of extensive computer simulations and well-developed theoretical approaches. From a technological point of view, the relevance of micro- and nanostructured materials and the presence of colloids in nature and everyday life motivates study of this rich field. In this thesis the phase behavior and the effective interactions of colloidal suspensions in bulk, in contact with surfaces, and in confined geometry are studied. For mixtures of particles with hard-core interactions the model introduced by Asakura, Oosawa and Vrij provides an appropriate starting-point. Based on that model the free-volume theory and the density functional theory are employed. In experimental systems one faces particles with properties such as the size or the shape which are described by a distribution. To capture that issue a generalized approach based on free-volume theory for treating mixtures of colloids and a polydisperse depletion agent is presented. Within that approach it is possible to treat size and morphology polydispersity. A depletion agent with a bimodal distribution possessing two length scales can be studied. Though the Asakura-Oosawa-Vrij model describes a simple fluid - a mixture of hard spheres and ideal polymer - the phenomenology is rather rich: in contact with a wall one finds layering and wetting effects and in confined geometry of a narrow pore one finds capillary condensation. The competition between both effects manifests itself in thermodynamic properties like the excess colloid adsorption and the solvation force between the two confining walls. Solvent phase separation complicates the evaluation of interparticle interactions between the solute particles. We address this question for the wall-colloid and the colloid-colloid geometry. For a non-spherical particle the effect of curvature on thermodynamic quantities is studied.