Download or read book A Theoretical Study of Bubble Motion in Surfactant Solutions written by Yanping Wang and published by . This book was released on 1999 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: We examine the effect of surfactants on a spherical gas bubble rising steadily in an infinite fluid at low and order one Reynolds number with order one and larger Peclet numbers. Our mathematical model is based on the Navier-Stokes equations coupled with a convection-diffusion equation together with appropriate interfacial conditions. The nonlinearity of the equations and boundary conditions, and the coupling between hydrodynamics and surfactant transport make the problem very challenging. When a bubble rises in a fluid containing surface-active agents, surfactant adsorbs onto the bubble surface at the leading edge, convects to the trailing edge by the surface flow and desorbs into the bulk along the interface. This adsorption develops a surface concentration gradient on the interface that makes the surface tension at the back end relatively lower than that at the front end, and thus retards the bubble velocity. Because of surfactant impurities unavoidably present in materials, this retardation can cause a problem in materials processing in space and glass processing when bubbles are created during chemical reactions. Thus the study of how to remobilize (remove the surfactant gradient on the surface) the bubble surface becomes necessary. Many studies have been done on this retarding effects of the surfactant on a moving bubble. However, most were focused on the retarding effect due to a trace amount of surfactant, in which case the bubble velocity monotonically decreases as the bulk concentration increases. The question of how to remobilize the bubble surface remains unanswered. In this work, we will show that the bubble velocity can be controlled by remobilizing the bubble interface using the surfactant concentration. This technique not only can be used to maximize the bubble velocity, but also can be used to maximize mass transfer on purifying materials and extracting materials from mixtures. In the first part of the work, we illustrate numerically that the bubble interface can be remobilized by increasing the bulk concentration of surfactant, for any fixed Peclet number, at low Reynolds number. For any fixed bulk concentration, the bubble velocity decreases with increasing Peclet number. The larger the Peclet number is the larger the required bulk concentration needed to bring the velocity back to the clean surface value. In the second part of the work, we will show that the remobilization still remains effective for order one Reynolds numbers. Moreover, when the rate of convection on the surface is much larger than the rate of diffusion at the back end, a stagnant cap develops near the back stagnation point that makes the bubble surface there act like a solid boundary. Wakes form at higher Reynolds numbers that drastically reduce the terminal velocity, and disappear as the bubble interface remobilizes. Finally, we consider the problem analytically for asymptotically large Peclet numbers. When the Peclet number is very large, a stagnant cap forms at the back end which makes one part of the bubble surface clean of surfactant, and the other part completely immobile. Also boundary layers develop along the bubble surface with different thicknesses on the clean part of the surface and on the stagnant cap. The asymptotic structures are obtained and the governing equations posed and partly addressed numerically and analytically.
Download or read book Experimental Study of Bubble Motion and Dissolution in Different Surfactant Solutions written by Juan Wang and published by . This book was released on 2001 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bubble Motion and Dissolution in Surfactant Solutions written by Ying Liao and published by . This book was released on 2001 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book IUTAM Symposium on Nonlinear Waves in Multi Phase Flow written by H.-C. Chang and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: The active field of multi-phase flow has undergone fundamental changes in the last decade. Many salient complex interfacial dynamics of such flows are now understood at a basic level with precise mathematical and quantitative characterization. This is quite a departure from the traditional empirical approach. At an IUTAM Symposium at Notre Dame, in 1999, some of the leading researchers in the field gathered to review the progress thus far and to contemplate future directions. Their reports are summarized in this Proceedings. Topics covered include solitary wave dynamics on viscous film flows, sheet formation and drop entrainment in stratified flow, wetting and dewetting dynamics, self-similar drop formation dynamics, waves in bubbly and suspension flow, and bubble dynamics. It is a unique and essential reference for applied mathematicians, physicists, research engineers, and graduate students to keep abreast of the latest theoretical and numerical developments that promise to transform multi-phase flow research.
Download or read book The Motion of Bubbles and Drops in Reduced Gravity written by R. Shankar Subramanian and published by Cambridge University Press. This book was released on 2001-04-09 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 2001 book provides a thorough review of the motion of bubbles and drops in reduced gravity.
Download or read book Interfacial Phenomena and the Marangoni Effect written by M. G. Velarde and published by Springer. This book was released on 2014-05-04 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marangoni (1878), provided a wealth of detailed information on the effects of variations of the potential energy of liquid surfaces and, in particular, flow arising from variations in temperature and surfactant composition. One aspect of this science is seen today to bear on important phenomena associated with the processing of modern materials. The role of the basic effect in technology was probably first demonstrated by chemical engineers in the field of liquid-liquid extraction. Indeed, phenomena attributable to Marangoni flows have been reported in innumerable instances relevant to modern technologies, such as in hot salt corrosion in aeroturbine blades; the drying of solvent-containing paints; the drying of silicon wafers used in electronics; in materials processing, particularly in metallic systems which have been suspected to demonstrate Marangoni flows.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2002 with total page 972 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanics and Physics of Bubbles in Liquids written by Leen van Wijngaarden and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: A IUTAM (International Union of Theoretical and Applied Mechanics) Sympo sium 'Mechanics and Physics of Bubbles in Liquids' was held at Pasadena, Calif., USA from 15 through 19 June 1981. The present volume contains the printed version of nearly all papers read at the Symposium. The study of the behaviour of bubbles in liquids was originally stimu lated by problems in cavitation and in boiling ofliquids. Today research is initiated by problems in many other fields as well. In this respect a growing interest from the side of biomechanics may be mentioned. Ordering of the papers could be done either according to the various mechanical and physical aspects of the subject or according to the fields of application. The presentaton at the Symposium contained a bit of both; there was a session on physico-chemical aspects for example and also a session on biological applications. The subdivision in this volume follows roughly the sessions in the Symposium. Most of them start with a paper of a survey nature, reporting progress made in recent years. Here, as in other fields of engineering science, one notes the important part played by experimental techniques and by numerical analysis.
Download or read book Computational Study of Adiabatic Bubble Growth Dynamics from Submerged Orifices in Aqueous Solutions of Surfactants written by Anirudh M. Deodhar and published by . This book was released on 2012 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growth dynamics of isolated gas bubbles (inception -> growth -> departure) emanating from a capillary-tube orifice submerged in isothermal pools of aqueous solutions of surfactants is computationally investigated. The Navier-Stokes equations are solved in the liquid and the gas phase. The evolution of the gas-liquid interface is tracked using a Volume-of-Fluid (VOF) method. Surfactant molecules in aqueous solutions have a tendency to diffuse towards the gas-liquid interface and are subsequently adsorbed onto it. This time dependent adsorption process gives rise to the dynamic surface tension behavior of the aqueous surfactant solutions. To computationally model this behavior, the species conservation equation for the surfactant is solved in the bulk fluid and is coupled with the dynamic adsorption-desorption of the surfactant on the interface. A new form of the surfactant transport equation is derived that was necessary to incorporate the interfacial transport in the volume-of-fluid method where the interface is spread over multiple grid cells. Computational results were obtained for bubble growth dynamics from a capillary orifice in a pool of pure water and in an aqueous solution of Sodium Dodecyl Sulphate (SDS). The evolving bubble shape and the flow field in the two phases in the pure liquid and in surfactant solution are compared for a variety of air flow rates (from 4 ml/min to 24 ml/min) in the constant bubble regime. To validate the computational model, the results for the transient shape and size of growing bubbles in pure water were compared with available experimental data and were found to be in excellent agreement. Results show that the dynamic surface tension relaxation gives rise to smaller bubble size at departure in aqueous surfactant solution compared to that in pure water. However, this effect is found to be a function of the air flow rate. At high air flow rates (24 ml/min), the short time for bubble growth allows relatively smaller drop in the surface tension and produces departure diameters similar to bubble diameters in water. At low air flow rates (4 ml/min), the departure time is much larger and allows for complete surface tension relaxation. As such the departure diameters at low air flow rates in aqueous surfactant solution are significantly smaller than those predicted in pure water. Also, the flow patterns around a growing bubble in surfactant solution are altered due to the non-uniform surfactant adsorption along the gas-liquid interface. The computational results elucidate the role of surfactant transport on bubble growth dynamics.
Download or read book A Parametric Investigation of Gas Bubble Growth and Pinch off Dynamics from Capillary tube Orifices in Liquid Pools written by Deepak Saagar Kalaikadal and published by . This book was released on 2012 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: The air-bubble dynamics phenomena in adiabatic liquid pools has been studied so as to present a better understanding of the parameters which that govern the process of ebullience, bubble growth and departure from a submerged capillary-tube orifice. The orifice diameter is found to directly dictate the bubble departure diameter, and the pinch-off is controlled by a characteristic neck-length. To study the role of orifice size on the growth and departure of adiabatic single bubbles, experiments were performed with different diameter capillary tubes submerged in of distilled de-ionized water as well as some other viscous liquids. A correlation has been developed based on the experimental data of this study along with those reported by several others in the literature. The predictions of this correlation agree very well with measured data for water as well as several other more viscous liquids. It is also found that the bubble departure diameter is the same as the orifice diameter when the latter equals twice the capillary length. The phenomenon of bubble necking and departure was explored experimentally and through a scaling analysis. Experiments were performed with five different liquids (water, ethanol, ethylene glycol, propylene glycol, and glycerol) to extract the departure neck-lengths for isolated gas bubbles at pinch-off from the capillary orifice. A scaling analysis of the experimental data indicated that the bubble neck-length at departure or pinch-off was predicted by a balance of buoyancy, viscous and surface tension forces. These were established to be represented by the Galilei and Morton numbers, and a power-law type predictive correlation has been shown to be in excellent agreement with the available data over a wide range of liquid properties. To characterize and model the growth and departure of single bubbles in different liquid pools, a theoretical model has been established. The motion of the gas-liquid interface has been modeled as a scaled force balance involving buoyancy, gas-momentum, pressure, surface tension, inertia and drag. With one-dimensional scaling of these forces, the model captures the incipience, growth, necking and departure of a bubble as it emerges from the orifice. Here necking and pinch-off is modeled based on the newly developed neck-length correlation. The results are compared with experimental data and are found to be in excellent agreement for a range of liquids, orifice sizes and flow rates. The predictions highlight the variations in bubble equivalent diameters at departure with orifice sizes, flow rates and fluid properties, and they further reiterate the well-established two-regime theory of bubble growth. The latter involves (a) the constant volume regime, where the bubble volume remains near constant and relatively independent of flow rate, and (b) the growing bubble regime, where the size of the bubble increases proportionately with the gas flow rate. Finally, the complex nature of ebullience in aqueous surfactant solutions has been studied using the reagents FS-50, SDS, and CTAB. The influence of the modulated liquid surface tension or more specifically, the role of the time dependent dynamic surface tension on the formation and departure of adiabatic bubbles has been investigated. Comparative studies have been undertaken to investigate the effect of time-dependent surface tension relaxation in surfactant solutions as opposed to ebullience in pure liquids with the same equilibrium surface tensions. Results highlight the effects of the surfactant's molecular weight on the adsorption-desorption kinetics, and the consequent influence on ebullience. It has been established that the bubbling characteristics in surfactant solutions are, in the first order, governed by the dynamic surface tension of the solute-solvent system.
Download or read book Bubble Dynamics and Interface Phenomena written by John R. Blake and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains papers presented at the IUTAM Symposium on Bubble Dynamics and Interface Phenomena held at the University of Birmingham from 6-9 September 1993. In many respects it follows on a decade later from the very successful IUTAM Symposium held at CALTECH in June 1981 on the Mechanics and physics of bubbles in liquids which was organised by the late Milton Plesset and Leen van Wijngaarden. The intervening period has seen major development with both experiment and theory. On the experimental side there have been ad vances with very high speed photography and data recording that provide detailed information on fluid and interface motion. Major developments in both computer hardware and software have also led to extensive improvement in our understand ing of bubble and interface dynamics although development is still limited by the sheer complexity of the laminar and turbulent flow regimes often associated with bubbly flows. The symposium attracts wide and extensive interest from engineers, physical, chemical, biological and medical scientists and applied mathematicians. The sci entific committee sought to achieve a balance between theory and experiment over a range of fields in bubble dynamics and interface phenomena. It was our intention to emphasise both the breadth and recent developments in these various fields and to encourage cross-fertilisation of ideas on both experimental techniques and theo retical developments. The programme, and the proceedings recorded herein, cover bubble dynamics, sound and wave propagation, bubbles in flow, sonoluminescence, acoustic cavitation, underwater explosions, bursting bubbles and ESWL.
Download or read book Geochemical Kinetics written by Youxue Zhang and published by Princeton University Press. This book was released on 2021-04-13 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a comprehensive exploration of geochemical kinetics--the application of chemical kinetics to geological problems, both theoretical and practical. Geochemical Kinetics balances the basic theories of chemical kinetics with a thorough examination of advanced theories developed by geochemists, such as nonisothermal kinetics and inverse theories, including geochronology (isotopic dating), thermochronology (temperature-time history), and geospeedometry (cooling rates). The first chapter provides an introduction and overview of the whole field at an elementary level, and the subsequent chapters develop theories and applications for homogeneous reactions, mass and heat transfer, heterogeneous reactions, and inverse problems. Most of the book's examples are from high-temperature geochemistry, with a few from astronomy and environmental sciences. Appendixes, homework problems for each major section, and a lengthy reference list are also provided. Readers should have knowledge of basic differential equations, some linear algebra, and thermodynamics at the level of an undergraduate physical chemistry course. Geochemical Kinetics is a valuable resource for anyone interested in the mathematical treatment of geochemical questions.
Download or read book Interfacial Rheology written by Reinhard Miller and published by CRC Press. This book was released on 2009-06-17 with total page 699 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book on interfacial rheology. It aims to describe both its history as well as the current, most frequently used experimental techniques for studying dilational and shear rheology of layers at liquid/gas and liquid/liquid interfaces. The book opens with a chapter on the fundamentals of interfacial rheology. All (16) contributions include the theoretical basis for the presented methodologies, and experimental examples are given.
Download or read book Solution Behavior of Surfactants written by K.L. Mittal and published by Springer. This book was released on 1982-09-30 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling and Simulation of Capsules and Biological Cells written by C. Pozrikidis and published by CRC Press. This book was released on 2003-05-28 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past three decades, considerable progress has been made in the mathematical analysis, modelling, and simulation of the fluid dynamics of liquid capsules and biological cells, and interest in this area is now at an all-time high. This book features a collection of chapters contributed by acknowledged leaders in the field who explore topics re
Download or read book Handbook of Ultrasonics and Sonochemistry written by Muthupandian Ashokkumar and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laminar Flow and Convective Transport Processes written by Howard Brenner and published by Elsevier. This book was released on 2013-10-22 with total page 761 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laminar Flow and Convective Transport Processes: Scaling Principles and Asymptotic Analysis presents analytic methods for the solution of fluid mechanics and convective transport processes, all in the laminar flow regime. This book brings together the results of almost 30 years of research on the use of nondimensionalization, scaling principles, and asymptotic analysis into a comprehensive form suitable for presentation in a core graduate-level course on fluid mechanics and the convective transport of heat. A considerable amount of material on viscous-dominated flows is covered. A unique feature of this book is its emphasis on scaling principles and the use of asymptotic methods, both as a means of solution and as a basis for qualitative understanding of the correlations that exist between independent and dependent dimensionless parameters in transport processes. Laminar Flow and Convective Transport Processes is suitable for use as a textbook for graduate courses in fluid mechanics and transport phenomena and also as a reference for researchers in the field.
