Download or read book Instabilities and Breakup in Thin Liquid Films written by Vineeth Chandran Suja and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid films having dimensions that are relatively small in the direction normal to their surface are commonly referred to as thin liquid films. Due to their prevalence in nature and due to their unique geometrical characteristics, a comprehensive understanding of thin film dynamics including instabilities and break-up within thin liquid films is of fundamental and practical interest. Practically this understanding is crucial to tuning the stability thin films in a number of important applications such as for stabilizing foams in foods and beverages, destabilizing foams in lubricants, avoiding surface irregularities in liquid coatings and treating ophthalmic disorders originating from the unnatural breakup of the tear film. Fundamentally, the microscopic thickness of these liquid films along with their large surface to volume ratio presents a convenient framework to investigate characteristics of two dimensional flows, and probe the effects of surface phenomenon such as evaporation and surfactant dynamics on fluid flows. Motivated by the importance of thin liquid films, in this thesis, we experimentally investigate the instabilities and break-up within thin liquid films. In the first part of the thesis (Chapters 2 - 4), we develop and optimize experimental tools and protocols for systematically studying thin liquid films. Notably, we show that single bubble/drop experiments are a convenient and complementary technique to study the dynamics of thin liquid films. Subsequently, we detail a new technique for automatically and robustly measuring the spatiotemporal thickness of thin liquid films - hyperspectral interferometry coupled with machine learning. Finally, we will also establish the operating regimes within which the size of bubbles formed on capillaries for single bubble experiments can be precisely controlled to avoid an air compressibility driven shape instabilities. In the subsequent parts of the thesis we utilize the developed tools to study four different problems - Bubble stability in worm like micellar (WLM) polymer solutions (Chapter 5), Lubricant foaming (Chapters 6 - 8), Drying of thin polymer films (Chapter 9) and Dewetting of the tear film (Chapter 10). In Chapter 5, we explore a problem relevant for the cosmetic industry, and characterize the drainage characteristics of thin films between bubbles and flat wormlike micellar solution - air interfaces. The supramolecular structure and elasticity of the wormlike micelles alters the dynamics of film drainage in WLM as compared to those in thin films containing pure surfactants. The unique features of film drainage include film elasticity driven 'dimple recoil' and a single step transition to a Newton black film beyond a critical film thickness. In Chapters 6 - 8, we explore a problem relevant for the lubricant industry, and study the stability of thin liquid films in lubricants with and without antifoams. Utilizing single bubble experiments, we reveal that the stability of thin films between bubbles in lubricant base oils are enhanced by Marangoni flows driven by the differential evaporation of the various components in the oil. Fundamentally, we also show that the spatiotemporal characteristics of these Marangoni flows are regulated by the concentration and volatility of the volatile species in the oil. Interestingly when the concentration of the volatile species approaches 50%, evaporation driven Marangoni flows become chaotic, with disordered spatial structure, chaotic fluctuations, spatially invariant mean film thickness statistics, high sensitivity to initial conditions, rapidly decaying spatial correlation and a power spectrum for thickness fluctuation that obeys a power law scaling that closely resembles the Kolmogorov's -5/3rd scaling. In the presence of filtered lubricants with antifoams, we reveal that the stability of thin films are positively correlated to the number of filtration cycles, and inversely correlated to the nominal filter pore size and the initial antifoam concentration. In Chapter 9 we explore a problem relevant for film coating, and study the drying of aqueous polymer solutions. Depending on the polymer concentration and the polymer diffusivities, we show that a classical Rayleigh-Taylor instability can develop within the drying solution. We also present the scaling laws describing the onset time of the instability as a function of the physical properties and initial polymer concentrations of the solutions. In Chapter 10 we report a platform to characterize the thickness of the tear film in vivo. By qualitatively comparing the dewetting characteristics observed in vivo with in vitro experiments, we will show that the mechanisms of dewetting is influenced by the presence of interfacial rheology. Further we also reveal that the spatial locations that are prone to dewetting are determined by the presence of interfacial rheology and the spatiotemporal drainage characteristics of the tear film. In Chapter 11 we summarize the findings in this thesis and discuss a number of interesting venues for future research.
Download or read book Instabilities in Falling Liquid Films written by Souradip Chattopadhyay and published by Mohammed Abdul Sattar. This book was released on 2023-11-21 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flows of thin film form the core of a large number of scientific, technological, and engineering applications. The occurrence of such flows can be observed in nature, for example on the windshield of vehicles in rainy weather. Thin film flows are also found in various engineering, geophysical, and biophysical ap- plications. Specific examples are nanofluidics, microfluidics, coating flows, intensive processing, tear-film rupture, lava flows, and dynamics of continental ice sheets. Important industrial applications of thin films include nuclear fusion research - for cooling the chamber walls surrounding the plasma, complex coating flows - where a thin film adheres to a moving substrate, distillation units, condensers, and heat exchangers, microfluidics, geophysical settings, such as gravity currents, mud, granular and debris flows, snow avalanches, ice sheet models, lava flows, biological and biophysical scenarios, such as flexible tubes, tear-film flows and many more. The dynamics of such films are quite complex and display rich behavior and this attracted many mathematicians, physicists, and engineers to the field. In the past three decades, the work in the area has progressed a lot with considerable stress on revealing the stability and dynamics of the film where the flow is driven by various forces such as gravity, capillarity, thermocapillarity, centrifugation, and inter- molecular. The flow may happen over structured or smooth and impermeable or slippery surfaces. The investigation approaches include modeling and analytical work, numerical simulations, and performing experiments to explain the instabilities that the film can exhibit. Direct analysis of the equations of the model of the interfacial flows is a very complicated mathematical exercise due to the existence of a free, evolving interface that bounds the liquid film. The mathematical complexity emerges from a number of things: (a) The Navier-Stokes (or Stokes or Euler) equations need to be solved in changing domains; (b) In certain applications one has to solve for the temperature or electrostatic or electromagnetic fields apart from the fluid equations; (c) Several nonlinear boundary conditions should be specified at the unknown interface(s) and (d) The solutions may not exist for all times. In fact in thin film problems, one may encounter finite-time singularities accompanied by topological transitions. The breakup of liquid jets is an example of that. However, in the subsequent chapters, we shall see that it is possible to use the different length scales appearing in thin film flows to our advantage. Thin films are characterized by much smaller length scales in the vertical direction as compared to those in the stream-wise direction. This gives rise to a small aspect ratio which makes the problem amenable for small amplitude perturbation expansions.
Download or read book Thin Liquid Films written by Ralf Blossey and published by Springer Science & Business Media. This book was released on 2012-05-22 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a treatise on the thermodynamic and dynamic properties of thin liquid films at solid surfaces and, in particular, their rupture instabilities. For the quantitative study of these phenomena, polymer thin films (sometimes referred to as “ultrathin”) have proven to be an invaluable experimental model system. What is it that makes thin film instabilities special and interesting? First, thin polymeric films have an important range of applications. An understanding of their instabilities is therefore of practical relevance for the design of such films. The first chapter of the book intends to give a snapshot of current applications, and an outlook on promising future ones. Second, thin liquid films are an interdisciplinary research topic, which leads to a fairly heterogeneous community working on the topic. It justifies attempting to write a text which gives a coherent presentation of the field which researchers across their specialized communities might be interested in. Finally, thin liquid films are an interesting laboratory for a theorist to confront a well-established theory, hydrodynamics, with its limits. Thin films are therefore a field in which a highly fruitful exchange and collaboration exists between experimentalists and theorists. The book stretches from the more concrete to more abstract levels of study: we roughly progress from applications via theory and experiment to rigorous mathematical theory. For an experimental scientist, the book should serve as a reference and guide to what is the current consensus of the theoretical underpinnings of the field of thin film dynamics. Controversial problems on which such a consensus has not yet been reached are clearly indicated in the text, as well as discussed in a final chapter. From a theoretical point of view, the field of dewetting has mainly been treated in a mathematically ‘light’ yet elegant fashion, often making use of scaling arguments. For the untrained researcher, this approach is not always easy to follow. The present book attempts to bridge between the ‘light’ and the ‘rigorous’, always with the ambition to enhance insight and understanding - and to not let go the elegance of the theory.
Download or read book The instability of thin liquid films in relation to coalescence written by Raymond John Barlett and published by . This book was released on 1973 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coupled Long wavelength Instabilities of Thin Liquid Films written by Miklós Vécsei and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stability of Thin Liquid Films written by Antonio Iván Jiménez-Laguna and published by . This book was released on 1991 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interactions in and Stability of Thin Liquid Films written by Narayan Chandra Mishra and published by . This book was released on 2005 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Instability of Thin Liquid Films on a Vertical Cylinder written by Elena Novbari and published by . This book was released on 2011 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The MEMS Handbook written by Mohamed Gad-el-Hak and published by CRC Press. This book was released on 2001-09-27 with total page 1386 pages. Available in PDF, EPUB and Kindle. Book excerpt: The revolution is well underway. Our understanding and utilization of microelectromechanical systems (MEMS) are growing at an explosive rate with a worldwide market approaching billions of dollars. In time, microdevices will fill the niches of our lives as pervasively as electronics do right now. But if these miniature devices are to fulfill their mammoth potential, today's engineers need a thorough grounding in the underlying physics, modeling techniques, fabrication methods, and materials of MEMS. The MEMS Handbook delivers all of this and more. Its team of authors-unsurpassed in their experience and standing in the scientific community- explore various aspects of MEMS: their design, fabrication, and applications as well as the physical modeling of their operations. Designed for maximum readability without compromising rigor, it provides a current and essential overview of this fledgling discipline.
Download or read book The Influence of Spreading Particles on the Stability of Thin Liquid Films written by Christiaan Gerrit Jan Bisperink and published by . This book was released on 1997 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rayleigh Plateau type Instabilities in Thin Liquid Films written by Sabrina Haefner and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thin Liquid Films written by Ivan Ivanov and published by Taylor & Francis. This book was released on 2023-02-06 with total page 1141 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive reference provided a systematic examination of both the theory and applications of thin liquid films - giving a critical review of major concepts and unresolved or controversial problems, as well as revealing experimental methods. It includes results previously unpublished. Combining the work of 20 leading researchers, Thin Liquid Films furnishes a fundamental overview of thermodynamics of thin liquid films. Generously illustrated with equations, tables and drawling and containing more than 2,200 citations to pertinent literature, this is an authoritative reference for physical, surface, and colloid chemists, biophysicists and physicists; chemical engineers and advanced graduate students in chemistry, chemical engineering, biophysics and physics.
Download or read book Hydrodynamic Instabilities written by François Charru and published by Cambridge University Press. This book was released on 2011-06-30 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: The instability of fluid flows is a key topic in classical fluid mechanics because it has huge repercussions for applied disciplines such as chemical engineering, hydraulics, aeronautics, and geophysics. This modern introduction is written for any student, researcher, or practitioner working in the area, for whom an understanding of hydrodynamic instabilities is essential. Based on a decade's experience of teaching postgraduate students in fluid dynamics, this book brings the subject to life by emphasizing the physical mechanisms involved. The theory of dynamical systems provides the basic structure of the exposition, together with asymptotic methods. Wherever possible, Charru discusses the phenomena in terms of characteristic scales and dimensional analysis. The book includes numerous experimental studies, with references to videos and multimedia material, as well as over 150 exercises which introduce the reader to new problems.
Download or read book Falling Liquid Films written by S. Kalliadasis and published by Springer Science & Business Media. This book was released on 2011-09-24 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: Falling Liquid Films gives a detailed review of state-of-the-art theoretical, analytical and numerical methodologies, for the analysis of dissipative wave dynamics and pattern formation on the surface of a film falling down a planar inclined substrate. This prototype is an open-flow hydrodynamic instability, that represents an excellent paradigm for the study of complexity in active nonlinear media with energy supply, dissipation and dispersion. It will also be of use for a more general understanding of specific events characterizing the transition to spatio-temporal chaos and weak/dissipative turbulence. Particular emphasis is given to low-dimensional approximations for such flows through a hierarchy of modeling approaches, including equations of the boundary-layer type, averaged formulations based on weighted residuals approaches and long-wave expansions. Whenever possible the link between theory and experiment is illustrated, and, as a further bridge between the two, the development of order-of-magnitude estimates and scaling arguments is used to facilitate the understanding of basic, underlying physics. This monograph will appeal to advanced graduate students in applied mathematics, science or engineering undertaking research on interfacial fluid mechanics or studying fluid mechanics as part of their program. It will also be of use to researchers working on both applied, fundamental theoretical and experimental aspects of thin film flows, as well as engineers and technologists dealing with processes involving isothermal or heated films. This monograph is largely self-contained and no background on interfacial fluid mechanics is assumed.
Download or read book Instability of Liquid Films in Constricted Capillaries written by Phillip Alan Gauglitz and published by . This book was released on 1986 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lacrimal Gland Tear Film and Dry Eye Syndromes 2 written by David A. Sullivan and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 1013 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past two decades, a significant international research effort has been di rected toward understanding the composition and regulation of the preocular tear film. This effort has been motivated by the recognition that the tear film plays an essential role in maintaining corneal and conjunctival integrity, protecting against microbial challenge, and preserving visual acuity. In addition, research has been stimulated by the knowledge that alteration or deficiency of the tear film, which occurs in countless individuals throughout the world, may lead to desiccation of the ocular surface, ulceration and perfo ration of the cornea, an increased incidence of infectious disease, and, potentially, pro nounced visual disability and blindness. To promote further progress in this field of vision research, the Second International Conference on the Lacrimal Gland, Tear Film and Dry Eye Syndromes: Basic Science and Clinical Relevance was held at the Southampton Princess Resort in Bermuda November 16-19, 1996. This conference was organized and directed by David A. Sullivan, Ph. D. , codirected by Darlene A. Dartt, Ph. D. , and Michele A. Meneray, Ph. D. , and sponsored by the Schepens Eye Research Institute (Boston, MA), an affiliate of Harvard Medical School. The meeting was designed to assess critically the current knowledge and "state of the art" research on the structure and function of lacrimal tissue, tears, and the ocular sur face in both health and disease.
Download or read book Fluid Dynamics at Interfaces written by Wei Shyy and published by Cambridge University Press. This book was released on 1999-09-28 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book experts discuss research and applications in interfacial fluid dynamics.
