The third volume in a series dedicated to colloids and interfaces, Drops and Bubbles in Contact with Solid Surfaces presents an up-to-date overview of the fundamentals and applications of drops and bubbles and their interaction with solid surfaces. The chapters cover the theoretical and experimental aspects of wetting and wettability, liquid-solid
1. Objective and Scope Bubbles, drops and rigid particles occur everywhere in life, from valuable industrial operations like gas-liquid contracting, fluidized beds and extraction to such vital natural processes as fermentation, evaporation, and sedimentation. As we become increasingly aware of their fundamental role in industrial and biological systems, we are driven to know more about these fascinating particles. It is no surprise, therefore, that their practical and theoretical implications have aroused great interest among the scientific community and have inspired a growing number of studies and publications. Over the past ten years advances in the field of small Reynolds numbers flows and their technological and biological applications have given rise to several definitive monographs and textbooks in the area. In addition, the past three decades have witnessed enormous progress in describing quantitatively the behaviour of these particles. However, to the best of our knowledge, there are still no available books that reflect such achievements in the areas of bubble and drop deformation, hydrodynamic interactions of deformable fluid particles at low and moderate Reynolds numbers and hydrodynamic interactions of particles in oscillatory flows. Indeed, only one more book is dedicated entirely to the behaviour of bubbles, drops and rigid particles ["Bubbles, Drops and Particles" by Clift et al. (1978)] and the authors state its limitations clearly in the preface: "We treat only phenomena in which particle-particle interactions are of negligible importance. Hence, direct application of the book is limited to single-particle systems of dilute suspensions.
Fluid flows that transfer heat and mass often involve drops and bubbles, particularly if there are changes of phase in the fluid in the formation or condensation of steam, for example. Such flows pose problems for the chemical and mechanical engineer significantly different from those posed by single-phase flows. This book reviews the current state of the field and will serve as a reference for researchers, engineers, teachers, and students concerned with transport phenomena. It begins with a review of the basics of fluid flow and a discussion of the shapes and sizes of fluid particles and the factors that determine these. The discussion then turns to flows at low Reynolds numbers, including effects due to phase changes or to large radial inertia. Flows at intermediate and high Reynolds numbers are treated from a numerical perspective, with reference to experimental results. The next chapter considers the effects of solid walls on fluid particles, treating both the statics and dynamics of the particle-wall interaction and the effects of phase changes at a solid wall. This is followed by a discussion of the formation and breakup of drops and bubbles, both with and without phase changes. The last two chapters discuss compound drops and bubbles, primarily in three-phase systems, and special topics, such as transport in an electric field.
The field of multiphase flows has grown by leaps and bounds in the last thirty years and is now regarded as a major discipline. Engineering applications, products and processes with particles, bubbles and drops have consistently grown in number and importance. An increasing number of conferences, scientific fora and archived journals are dedicated to the dissemination of information on flow, heat and mass transfer of fluids with particles, bubbles and drops. Numerical computations and "thought experiments" have supplemented most physical experiments and a great deal of the product design and testing processes. The literature on computational fluid dynamics with particles, bubbles and drops has grown at an exponential rate, giving rise to new results, theories and better understanding of the transport processes with particles, bubbles and drops. This book captures and summarizes all these advances in a unified, succinct and pedagogical way. Contents: Fundamental Equations and Characteristics of Particles, Bubbles and Drops; Low Reynolds Number Flows; High Reynolds Number Flows; Non-Spherical Particles, Bubbles and Drops; Effects of Rotation, Shear and Boundaries; Effects of Turbulence; Electro-Kinetic, Thermo-Kinetic and Porosity Effects; Effects of Higher Concentration and Collisions; Molecular and Statistical Modeling; Numerical Methods-CFD. Key Features Summarizes the recent important results in the theory of transport processes of fluids with particles, bubbles and drops Presents the results in a unified and succinct way Contains more than 600 references where an interested reader may find details of the results Makes connections from all theories and results to physical and engineering applications Readership: Researchers, practicing engineers and physicists that deal with any aspects of Multiphase Flows. It will also be of interest to academics and researchers in the general fields of mechanical and chemical engineering.
The book aims at describing the most important experimental methods for characterizing liquid interfaces, such as drop profile analysis, bubble pressure and drop volume tensiometry, capillary pressure technique, and oscillating drops and bubbles.
The shape of drops and bubbles is the centre of interest for many interfacial scientists. This book describes the most recent accomplishments to make use of drops and bubbles in fundamental research and application. After a general introduction into the mechanics of liquid menisci, chapters are dedicated to methods based on drops or bubbles. The chapters about the three main drop experiments provide the theoretical basis, a description of experimental set-ups, specific advantages and disadvantages, correction and calibration problems, experimental examples and their interpretation: pendent and sessile drop, drop volume, and spinning drop technique. The chapter about capillary pressure methods summarises different techniques and gives examples of applications, for instance measurements under microgravity. The maximum bubble pressure technique as a particular capillary pressure method is described, with emphasis on the most recent developments which made this technique applicable to extremely short adsorption times, down to the range of milliseconds and less. Problems connected with aerodynamics and hydrodynamics are discussed and used to show the limits of this widely used standard method. The oscillating bubble technique provides information not available by other techniques, for example about the dilational rheology of adsorption layers and relaxation processes at the interface. The description of rising bubbles in surfactant solutions will contain the hydrodynamic basis as well as the theoretical description of the effect of interfacial layers on the movement of bubbles. Besides the theoretical basis experimental data, such as water purification, flotation processes etc. and the relevance for practical applications will be presented. The chapter about lung alveols demonstrates how important bubbles built by biological membranes are in everyday life. The relevance for medicine and biology as well as model studies is discussed. An important example for the application of drops is metallurgy, where the surface tension of metals and alloys is an important parameter for many applications. The chapters on drop shape analysis by using fibre technique and on force measurements between emulsion droplets are of much practical relevance. Lists of references and symbols are given separately at the end of each chapter while a common subject index is given at the end of the book.
"We've all spent summers past blowing bubbles in the backyard. But the humble bubble (and its opposite, the droplet) are fascinating cornerstones of the world around us. This book, breathtaking in its scope, describes for a general reader (no math, no physics, no equations) the compelling behavior of these seemingly simple objects. Young reveals the secrets of successful springboard diving, whether knuckle cracking gives you arthritis, and why dolphins can't go faster. The realm of droplets allows our author to showcase why the sky is blue, how atom smashers work, and the rich source of science that is the kitchen faucet. He explores collections of bubbles--foams--and discusses the early years of Margaret Thatcher, how a metallic foam might save the planet, and the never-ending quest for the perfect pint. Then, by looking at soap films, he tells you how to construct a soapy computer, why coffee rings form, and exactly how a detergent gets dishes clean. Beyond these basics, Young shows how humans put bubbles to use, whether in technology (refining minerals, making concrete harder, or generating light) or in medicine (cleaning wounds with hydrogen peroxide, the debilitating process of the bends, and how pharmaceutical bubbles can make ultrasounds far clearer). This is more than a book that explains science. It is a love letter written to sing the praises of the bubble, and can be read by the bright middle schooler on upward"--
The study of capillarity is in the midst of a veritable explosion. What is offered here is not a comprehensive review of the latest research but rather a compendium of principles designed for the undergraduate student and for readers interested in the physics underlying these phenomena.
