Instability Of Thin Liquid Films On A Vertical Cylinder
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Instability Of Thin Liquid Films On A Vertical Cylinder
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Author : Elena Novbari
language : en
Publisher:
Release Date : 2011
Instability Of Thin Liquid Films On A Vertical Cylinder written by Elena Novbari and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The Instability Of Thin Liquid Films In Relation To Coalescence
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Author : Raymond John Barlett
language : en
Publisher:
Release Date : 1973
The Instability Of Thin Liquid Films In Relation To Coalescence written by Raymond John Barlett and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1973 with categories.
Thin Liquid Films
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Author : Ralf Blossey
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-05-22
Thin Liquid Films written by Ralf Blossey and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-05-22 with Science categories.
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.
Falling Liquid Films
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Author : S. Kalliadasis
language : en
Publisher: Springer Science & Business Media
Release Date : 2011-09-24
Falling Liquid Films written by S. Kalliadasis and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-09-24 with Mathematics categories.
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.
Experiments On The Stability Of Thin Falling Liquid Films On A Solid Vertical Cylindrical Surface
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Author : Gregory St. Clair Massey
language : en
Publisher:
Release Date : 1993
Experiments On The Stability Of Thin Falling Liquid Films On A Solid Vertical Cylindrical Surface written by Gregory St. Clair Massey and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Liquid films categories.
Stable Localized Patterns In Thin Liquid Films
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Author : Robert J. Deissler
language : en
Publisher:
Release Date : 1991
Stable Localized Patterns In Thin Liquid Films written by Robert J. Deissler and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with Liquid films categories.
Characteristics And Applications Of Thin Liquid Films Flowing Down High Curvature Surfaces
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Author : Abolfazl Sadeghpour
language : en
Publisher:
Release Date : 2020
Characteristics And Applications Of Thin Liquid Films Flowing Down High Curvature Surfaces written by Abolfazl Sadeghpour and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Thin liquid films flowing down vertical fibers present a wealth of complex and interesting interfacial dynamics, including the formation of droplets and traveling wave patterns. Such dynamics is an important consideration in various applications, such as fiber coating and direct-contact heat and mass exchangers which take advantage of extended interfacial areas and larger residence time afforded by the bead formation along the fiber. A rigorous investigation on the fluid dynamics and interfacial heat and mass transfer mechanism of liquid films flowing along vertical strings is, thus, needed to enable physics-based optimization and analysis of multi-string designs for the mentioned applications. This dissertation presents a combination of experimental, numerical, and theoretical study of liquid films flowing down a vertical fiber. Additionally, we report a first-ever combined experimental and theoretical study of the instability in thin film flows of a high-surface energy low-viscosity liquid (i.e. water) along cotton threads. Utilizing our finding, we then adapted the multi-string configuration for novel applications, such as humidification, dehumidification, and particle capturing. We started with a thorough experimental study of viscous liquids flowing down vertical fibers (i.e. polymer strings). Previous researchers suggested that the liquid film thickness and velocity profiles of nearly flat portion of a liquid film that precedes the onset of instability can be specified regardless of the nozzle geometry. As a result, they largely overlooked the effects of nozzle on the pattern and characteristics of the downstream flow. We performed a systematic experimental study by varying the nozzle inner diameter from 0.5 to 3.2 mm at various mass flow rates (from 0.02 to 0.08 g/s). We focused on experimental conditions within the Rayleigh Plateau (RP) instability regime, where traveling wave solution emerges and generates uniformly-spaced drop-like liquid beads on vertical fibers. Our results emphasize the strong influence of nozzle geometry on the flow regime and the flow characteristics. We experimentally measured the thickness of the flat film portion after the nozzle, which we term the preinstability thickness, and identified it as a flow parameter which governs the size, spacing, and velocity of downstream liquid beads. We also performed a set of complementary numerical simulations that solves the full Navier-Stokes equations to predict the fluid dynamics of the downstream flow, such as the liquid velocity profile along the fiber. To better understand the influence of nozzle diameter on the regime transition as well as the downstream bead dynamics, we performed a detailed theoretical study of viscous flow down a vertical fiber. We proposed a full lubrication model that includes slip boundary conditions, nonlinear curvature terms, and a film stabilization term, and compared the predicted film dynamics against the experimental results. Numerical simulations confirm that in addition to fiber sizes and flow rates, the downstream flow regime and characteristics are also significantly affected by the nozzle geometry. Moreover, the effect of film stabilization term on the flow pattern and bead characteristic is studied. We also compared our results with previously studied theoretical methods, such as CM model, linear curvature model, and full curvature model. Additionally, we leveraged our successful demonstration of stable water flow along a vertical cotton string to construct a multi-string water vapor capturing system, where a massive array traveling water beads act as the condensation interface for water vapor in the counterflowing air stream. These water beads form through intrinsic flow instability and offer high curvature surfaces to enhance the vapor condensation rate. The effects of the water flow rate and air velocity on the condensation rates are experimentally characterized. The gas-stream pressure drop of the design is also measured. The condensation rates and gas-stream pressure drop from our multi-string dehumidifier is compared with the existing dehumidifier designs. A simplified theoretical model is also presented as the starting point for further optimizing the design parameters of our device. Finally, we extended our investigation for potential applications of the cotton-based multi-string configuration and proposed a novel string-based particle collector. Wet electrostatic precipitators (WESP) are generally highly effective for collecting fine particles in air streams from various sources such as diesel engines, power plants, and oil refineries. However, some limiting factors, such as high water usage, poses restrictions. Our new compact particle collector utilizes an array of traveling water beads on vertical cotton strings to collect the pre-charged particles in the counterflowing air stream. The experimental and numerical investigation presented in this work is performed to determine the collection efficiency and the optimal water flow rate for our new design. The unique configuration of our string-based counterflow WESP in this study exhibits high number-based collection efficiency, > 80%, for a wide range of particle diameters, 10 nm - 2.5 m, while decreasing the water usage significantly, which can provide a basis for the design of more water-efficient WESPs.
Instabilities In Falling Liquid Films
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Author : Souradip Chattopadhyay
language : en
Publisher: Mohammed Abdul Sattar
Release Date : 2023-11-21
Instabilities In Falling Liquid Films written by Souradip Chattopadhyay and has been published by Mohammed Abdul Sattar this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-11-21 with categories.
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.
Electrified Pressure Driven Instability In Thin Liquid Films
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Author : Hadi Nazaripoor
language : en
Publisher:
Release Date : 2018
Electrified Pressure Driven Instability In Thin Liquid Films written by Hadi Nazaripoor and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Technology categories.
The electrified pressure-driven instability of thin liquid films, also called electrohydrodynamic (EHD) lithography, is a pattern transfer method, which has gained much attention due to its ability in the fast and inexpensive creation of novel micro- and nano-sized features. In this chapter, the mathematical model describing the dynamics and spatiotemporal evolution of thin liquid film is presented. The governing hydrodynamic equations, intermolecular interactions, and electrostatic force applied to the film interface and assumptions used to derive the thin film equation are discussed. The electrostatic conjoining/disjoining pressure is derived based on the long-wave limit approximation since the film thickness is much smaller than the characteristic wavelength for the growth of instabilities. An electrostatic model, called an ionic liquid (IL) model, is developed which considers a finite diffuse electric layer with a comparable thickness to the film. This model overcomes the lack of assuming very large and small electrical diffuse layer, as essential elements in the perfect dielectric (PD) and the leaky dielectric (LD) models, respectively. The ion distribution within the IL film is considered using the Poisson-Nernst-Planck (PNP) model. The resulting patterns formed on the film for three cases of PD-PD, PD-IL, and IL-PD double layer system are presented and compared.
Stability Of Thin Liquid Films
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Author : Antonio Iván Jiménez-Laguna
language : en
Publisher:
Release Date : 1991
Stability Of Thin Liquid Films written by Antonio Iván Jiménez-Laguna and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with categories.
