Numerical Modeling and Investigation of Speading and Drying of Colloidal Droplets PDF Download

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 158

View

Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
10H2O) droplets are compared with the model predictions. Further, proper choices of the numerical parameters are sought in order to have successful iteration loops. The model successfully estimated the weight and temperature histories of colloidal silica, dried at air temperatures of 101oC and 178oC, and skimmed milk, dried at air temperatures of 50oC and 90oC, droplets. However, the model failed to predict both the weight and the temperature histories of Na2SO4⋅.

Author: Rajneesh Bhardwaj
Publisher:
ISBN: 9781449972141
Category :
Languages : en
Pages : 176

View

Book Description
The high, fast and local heat transfer associated with the deposition and evaporation of a single droplet on a flat surface has potential applications in spray evaporative cooling. Controlled evaporation of microdroplets containing colloidal particles can be used to manufacture nanowires, explosive crystalline layers and DNA spots for gene expression analysis. The physics of this phenomenon is a complex interplay of fluid dynamics in presence of a severely deforming free surface, wetting line motion, convective and conductive heat transfer, mass transfer due to evaporation and advection-diffusion of particles inside the droplet. In this book, Rajneesh Bhardwaj proposes a numerical modeling to investigate the interplay of transport phenomena during droplet impact and evaporation, for the case of a pure liquid or a colloidal solution. Comparions of numerical results with available or in-house experiments are made wherever possible.

Author: David Brutin
Publisher: Royal Society of Chemistry
ISBN: 1839161205
Category : Science
Languages : en
Pages : 244

View

Book Description
Coffee rings, paint drying, blood splatter are all examples of complex fluids drying. Understanding the phenomena of complex fluid drops with respect to drying is important for technology and a lot of research in academia and industry is poured into this topic. This book addresses this industrially important area and provides a thorough grounding to the field. Addressing the fundamental underpinnings of wetting, spreading and drying, the book then takes the reader through key applications grouped into themes, including colloidal droplets (used in printing) and biological (e.g. bloodstain analysis for forensics). With a section on modelling and simulation to balance experiment with computational tools, this book will appeal to anyone working in complex fluids across classical fluid mechanics, soft matter, and chemical, biological and mechanical engineering

Author: Sushrutha Reddy Gujjula
Publisher:
ISBN:
Category :
Languages : en
Pages : 63

View

Book Description
The present study of droplet spreading has many industrial applications of which, ink jet printing, plasma spraying, fire extinguishers are but a few. These applications need a detailed and fundamental understanding of the droplet spreading physics, which is divided into four phases. In the present work, two of these phases, namely, the spreading phase, and equilibrium phase have been analyzed. Since droplet spreading is a dynamic phenomenon where the surface of the droplet changes with time, capturing these changes requires a two-phase approach called volume of fluid (VOF) method. The VOF method uses an advection equation to determine the interface between the liquid and the surrounding air. At the intersection of this interface with a solid boundary is a point common to all three phases, solid, gas, and liquid. At the liquid-solid-gas contact point, contact-angle is the angle between the solid surface and the tangent to the liquid-gas interface, the contact-angle can also vary with time. A number of contact-angle models have been proposed and used in simulations of droplet spreading research reported in literature. The present study is a systematic analysis of the most widely used contact-angle models, which include both, static and dynamic contact-angle models, on surfaces with varying wettability, i.e. hydrophilic and hydrophobic surfaces. To compile the contact-angle models, an open source code, OpenFOAM was used. Results from simulations are presented and compared with those from experiments, conducted by Pasandideh Fard et al. [21] and Vadillo et al. [26]. In addition, two parameters, called the maximum spreading diameter, and the equilibrium spreading diameter, were also analyzed in detail. The results indicated that, using the static contact angle models over-predicted the maximum spreading diameter for the hydrophilic case, whereas the equilibrium spreading diameter was under-predicted. In case of the hydrophobic surface, the maximum spreading diameter was predicted well, but the equilibrium spreading diameter was slightly under-predicted. Simulations using the dynamically varying contact angles with respect to empirical correlations and theoretical expressions slightly under-predicted the overall trend of the spreading diameter. But observations of the maximum and equilibrium diameters were predicted better. Using the experimentally measured contact-angle values as a boundary condition in the simulations improved the dynamic spreading diameter prediction.

Author: Huimin Liu
Publisher: William Andrew
ISBN: 0815518943
Category : Technology & Engineering
Languages : en
Pages : 541

View

Book Description
This is the first book to encompass the fundamental phenomenon, principles, and processes of discrete droplets of both normal liquids and melts. It provides the reader with the science and engineering of discrete droplets, and provides researchers, scientists and engineers with the latest developments in the field. The book begins with a systematic review of various processes and techniques, along with their applications and associations with materials systems. This is followed by a description of the phenomena and principles in droplet processes. Correlations, calculations, and numerical modeling of the droplet processes provide insight into the effects of process parameters on droplet properties for optimization of atomizer design. Droplets are found in the areas of metallurgy, materials, automotive, aerospace, medicine, food processing, agriculture, and power generation, and encountered in a huge range of engineering applications.

Author: Bernard P. Binks
Publisher: Cambridge University Press
ISBN: 1139458183
Category : Technology & Engineering
Languages : en
Pages : 500

View

Book Description
The understanding of how small solid particles operate at liquid interfaces is minimal. This book brings together the topics actively being investigated, with contributions from experts in the field. It will be of interest to researchers in chemistry, physics, chemical engineering, pharmacy, food science and materials science.

Author: Juan Rodríguez-Hernández
Publisher: Springer
ISBN: 3319174312
Category : Technology & Engineering
Languages : en
Pages : 291

View

Book Description
Pattern formation is a fascinating and challenging aspect in polymer science. This book describes a number of unconventional approaches developed to control the morphology of polymer surfaces and materials, from random or simple patterns to complex structures. Specialists provide an up-to-date and complete overview of each technique in their respective field.

Author: David Brutin
Publisher: Academic Press
ISBN: 0128008083
Category : Science
Languages : en
Pages : 464

View

Book Description
Droplet Wetting and Evaporation provides engineers, students, and researchers with the first comprehensive guide to the theory and applications of droplet wetting and evaporation. Beginning with a relevant theoretical background, the book moves on to consider specific aspects, including heat transfer, flow instabilities, and the drying of complex fluid droplets. Each chapter covers the principles of the subject, addressing corresponding practical issues and problems. The text is ideal for a broad range of domains, from aerospace and materials, to biomedical applications, comprehensively relaying the challenges and approaches from the different communities leading the way in droplet research and development. Provides a broad, cross-subject coverage of theory and application that is ideal for engineers, students and researchers who need to follow all major developments in this interdisciplinary field Includes comprehensive discussions of heat transfer, flow instabilities, and the drying of complex fluid droplets Begins with an accessible summary of fundamental theory before moving on to specific areas such as heat transfer, flow instabilities, and the drying of complex fluid droplets

Author: Fei Gao
Publisher:
ISBN:
Category : Blood
Languages : en
Pages : 67

View

Book Description
Droplet dynamics involves multi-scale forces from inertia body force, interior viscous shear stress to surface tension. The main purpose of this thesis is to simulate the normal impact of a liquid droplet on a hydrophobic surface by solving for the Navier-Stokes equations. The numerical results obtained is used to evaluate the effects of variable parameters on the droplet deformation evolution. The numerical simulation also works as a complimentary part of the experimental exploration, by the group members in the Droplet-Surface Impact Project in Northeastern University. The computational tool used is OpenFOAM, an open source CFD software package licensed and distributed by the OpenFOAM Foundation. The specific solver used is interFoam for this two phase problem. Water is modeled as a representative of the Newtonian fluids, while blood is modeled to represent non-Newtonian fluids. Multiple variables of the droplet-surface impact are investigated numerically: initial velocity, droplet diameter, transport properties, all of which contributes to a variation of the Weber number. The numerical results obtained for water droplets are supported by experimental data and also semi-empirical correlations. The spreading behavior and generation of ripples are in good agreement with that observed in the experimental tests. As the capillary effects become more dominant in the recoiling period, a discrepancy starts to show by a pre-maturely generated secondary droplet in simulation. Possible reasons are speculated for this discrepancy between numerical and experimental results. In the numerical comparison between water and blood droplets, a resemblance of droplet behavior in the initial spreading process is observed, while the recoiling process shows differences: blood droplets rebound in an "irregular" way compared to water droplets. The difference in deformation behaviors caused by varied transport properties leads to a way of distinguishing liquids by simple droplet-surface impact tests.