Electrified Pressure-Driven Instability in Thin Liquid Films

Electrified Pressure-Driven Instability in Thin Liquid Films PDF Author: Hadi Nazaripoor
Publisher:
ISBN:
Category : Technology
Languages : en
Pages :

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Book Description
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.

Electrified Pressure-Driven Instability in Thin Liquid Films

Electrified Pressure-Driven Instability in Thin Liquid Films PDF Author: Hadi Nazaripoor
Publisher:
ISBN:
Category : Technology
Languages : en
Pages :

Get Book Here

Book Description
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.

Electric Field

Electric Field PDF Author: Mohsen Sheikholeslami Kandelousi
Publisher: BoD – Books on Demand
ISBN: 1789231868
Category : Technology & Engineering
Languages : en
Pages : 324

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Book Description
In the present book, various applications of electric field are introduced in health and biology like treating cancer and cell sorting and in engineering and technological applications like enhancing the heat transfer, colloidal hydrodynamics and stability, and lithography. Electric field is defined as a force field arising from the electric charges. Depending on the nature of the material (the ability to polarize) and the inherent or attained surface charges, the response of the electric field varies.

The instability of thin liquid films in relation to coalescence

The instability of thin liquid films in relation to coalescence PDF Author: Raymond John Barlett
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Electrohydrodynamic Instabilities in Thin Liquid Trilayer Films

Electrohydrodynamic Instabilities in Thin Liquid Trilayer Films PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Experiments by Dickey and Leach show that novel pillar shapes can be generated from electrohydrodynamic instabilities at the interfaces of thin polymer/polymer/air trilayer films. In this paper, we use linear stability analysis to investigate the effect of free charge and ac electric fields on the stability of trilayer systems. Our work is also motivated by our recent theoretical study which demonstrates how ac electric fields can be used to increase control over the pillar formation process in thin liquid bilayer films. For perfect dielectric films, the effect of an AC electric field can be understood by considering an equivalent DC field. Leaky dielectric films yield pillar configurations that are drastically different from perfect dielectric films, and AC fields can be used to control the location of free charge within the trilayer system. This can alter the pillar instability modes and generate smaller diameter pillars when conductivities are mismatched. The results presented here may be of interest for the creation of complex topographical patterns on polymer coatings and in microelectronics.

Falling Liquid Films

Falling Liquid Films PDF Author: S. Kalliadasis
Publisher: Springer Science & Business Media
ISBN: 1848823673
Category : Mathematics
Languages : en
Pages : 446

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Book Description
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.

Instability of Thin Liquid Films on a Vertical Cylinder

Instability of Thin Liquid Films on a Vertical Cylinder PDF Author: Elena Novbari
Publisher:
ISBN:
Category :
Languages : en
Pages : 134

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Book Description


Polymers, Liquids and Colloids in Electric Fields

Polymers, Liquids and Colloids in Electric Fields PDF Author: Yoav Tsori
Publisher: World Scientific
ISBN: 9814271691
Category : Science
Languages : en
Pages : 294

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Book Description
This unique book aims to expose the reader to a wide range of phenomena occurring when soft matter systems are put under the influence of an external electric field. The book shows how an electric field can be used to affect objects at the submicron scale, and how it controls the phase behavior of liquids and polymers. The main focus is on the basic underlying mechanisms. Some technological applications are dealt with as well. Book chapters are arranged in a logical order, from OC simpleOCO systems to more complicated ones. In addition, each topic is covered by the mixed bag of theory, experiment and simulation; and this will give the reader a broad perspective of the underlying physical phenomena."

Interfacial Fluid Mechanics

Interfacial Fluid Mechanics PDF Author: Vladimir S. Ajaev
Publisher: Springer Science & Business Media
ISBN: 1461413419
Category : Technology & Engineering
Languages : en
Pages : 219

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Book Description
Interfacial Fluid Mechanics: A Mathematical Modeling Approach provides an introduction to mathematical models of viscous flow used in rapidly developing fields of microfluidics and microscale heat transfer. The basic physical effects are first introduced in the context of simple configurations and their relative importance in typical microscale applications is discussed. Then, several configurations of importance to microfluidics, most notably thin films/droplets on substrates and confined bubbles, are discussed in detail. Topics from current research on electrokinetic phenomena, liquid flow near structured solid surfaces,evaporation/condensation, and surfactant phenomena are discussed in the later chapters.

Coupled Long-wavelength Instabilities of Thin Liquid Films

Coupled Long-wavelength Instabilities of Thin Liquid Films PDF Author: Miklós Vécsei
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Electrohydrodynamic Patterning of Functional Materials

Electrohydrodynamic Patterning of Functional Materials PDF Author: Pola Goldberg Oppenheimer
Publisher: Springer Science & Business Media
ISBN: 3319007831
Category : Technology & Engineering
Languages : en
Pages : 148

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Book Description
This thesis explores a route to induce and control the structure formation process in thin films by the use of strong electric fields. We investigate, establish and apply the use of the electrohydrodynamic (EHD) lithography as a versatile patterning tool on the sub-micrometre and nanometre length scales for functional materials. Thin films are ubiquitous, they are found in nature and used in almost every aspect of daily life. While film instabilities are often undesirable in nature and technology, they can be utilized to produce structures by precisely controlling the destabilization of the film. EHD lithography utilizes instabilities induced by means of an electric field to fabricate periodic structures. EHD patterning is set to become a competitive candidate for low-cost lithographic technology for a number of applications. Herein, the applied potential of this lithographic process is explored by expanding its applicability to a broad range of materials and by a simultaneous patterning of multilayer systems or functional polymers yielding hierarchical architectures with novel functionalities. EHD pattern formation enables for instance, the fabrication of multi-scale structured arrays as surface enhanced Raman scattering (SERS)-active platforms. Furthermore, crystalline and conductive polymers are patterned using the EHD approach and the underlying structure formation mechanisms are discussed. This extension towards functional material systems offers interesting prospects for potential applications. Findings of this thesis are very promising for use in optoelectronic devices.