Download or read book A study of droplet deformation written by Hannah Fry and published by Lulu.com. This book was released on 2012-09-14 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: In both engineering and medical applications it is often useful to use the knowledge of the conditions under which adhering liquid droplets appear, deform and interact with surrounding fluids, in order to either remove or create them. Examples include the de-wetting of aircraft surfaces and the process of injecting glue into the bloodstream in the treatment of aneurysms. In this study, we look at various methods of modelling a particular class of droplets - those attached to a wall in the presence of an external shear flow.
Download or read book A Fundamental Study of Super critical Droplet Deformation and Break up Through a Miscible Fluid Analog written by Chad Mitts and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Morphology and Development of Droplet Deformation Under Flow Within Microfluidic Devices written by Molly K. Mulligan and published by . This book was released on 2012 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfluidics is the science of processing microliters or less of fluid at a time in a channel with dimensions on the order of microns. The small size of the channels allows fluid properties to be studied in a world dominated by viscosity, surface tension, and diffusion rather than gravity and inertia. Microfluidic droplet generation is a well studied and understood phenomena, which has attracted attention due to its potential applications in biology, medicine, chemistry and a wide range of industries. This dissertation adds to the field of microfluidic droplet studies by studying individual droplet deformation and the process of scaling-up microfluidic devices for industrial use. The study of droplet deformation under extensional and mixed shear and extensional flows was performed within a microfluidic device. Droplets were generated using a flow-focusing device and then sent through a hyperbolic contraction downstream of the droplet generator. The hyperbolic contraction allowed the smallest droplets to be deformed by purely extensional flows and for the larger droplets to experience mixed extensional and shear flows. The shear resulted from the proximity of the droplet to the walls of the microfluidic channel. The continuous phase in all of these devices was oil and the dispersed phase was water, an aqueous surfactant solution, or an aqueous suspension of colloidal particles. Droplet deformation dynamics are affected by the use of surfactants and colloidal particles, which are commonly used to stabilize emulsion droplets again coalescence. Microfluidic droplet generating devices have many potential industrial applications, however, due to the low output of product from a single droplet generating device, their potential has not been realized. Using six parallel flow-focusing droplet generators on a single chip, the process of microfluidic droplet formation can be scaled up, thus resulting in a higher output of droplets. The tuning of droplet size and production frequency can be achieved on chip by varying the outlet tubing lengths, thus allowing for a single device to be used to generate a range of droplet sizes.
Download or read book Droplet Deformation Prediction with the Droplet Deformation and Breakup Model Ddb written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-13 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results. Vargas, Mario Glenn Research Center WBS 648987.02.02.03.10
Download or read book Droplet Deformation Prediction with the Droplet Deformation and Breakup Model written by Mario Vargas and published by BiblioGov. This book was released on 2013-07 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results.
Download or read book Boundary Integral and Singularity Methods for Linearized Viscous Flow written by C. Pozrikidis and published by Cambridge University Press. This book was released on 1992-02-28 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: In addition to theory, this study focuses on practical application and computer implementation in a coherent introduction to boundary integrals, boundary element and singularity methods for steady and unsteady flow at zero Reynolds numbers.
Download or read book Droplet Deformation Prediction with the Droplet Deormation and Break Up Model written by Mario Vargas and published by BiblioGov. This book was released on 2013-06 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results.
Download or read book A Study on the Deformation and Breakup of Supercooled Large Droplets at the Leading Edge of an Airfoil written by Belen Veras-Alba and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ice accretion is an issue that has affected aircraft since the early years of powered ight. Although it was a known problem, the full extent was not known. Both small and large droplets were of concern. The effects of both were countered with ice protection systems based initially on computer codes that predict the size, shape, and location of ice on aerodynamic surfaces for small droplets. The codes have been tested and validated for the conditions described in Federal Aviation Regulation Part 25 Appendix C (small droplets, up to 50 m) and aircraft only had to be certied for those conditions. Supercooled large droplets (SLD) reach locations further aft on the surfaces than small droplets making the ice protection systems insufficient in SLD icing conditions. The protection systems remove ice but do not reach the limits of the SLD ice and ridges remain on the wing surfaces which continue to negatively impact the performance of the aircraft. Certication regulations regarding SLD have been implemented but the codes do not yet accurately predict ice accretion due to SLD. To validate the codes, experimental data on the behavior of larger droplets when impacting a lifting surface are necessary. The results of an experimental study on the deformation and breakup of supercooled droplets near the leading edge of an airfoil are presented. The experiment was conducted in the Adverse Environment Rotor Test Stand (AERTS) facility at The Pennsylvania State University with the intention of comparing the results to prior room temperature droplet deformation results. To collect the data, an airfoil model was placed on the tip of a rotor blade mounted onto the hub in the AERTS chamber. The model was moved at speeds between 50 and 80 m/s while a monosize droplet generator produced droplets of various sizes which fell from above, perpendicular to the path of the model. The temperature in the chamber was set to -20C. The supercooled droplets were produced by maintaining the temperature of the water at the droplet generator under 5C.The supercooled state of the droplets was determined by measurement of the temperature of the droplets at various distances below the tip of the droplet generator. A prediction code was also used to estimate the temperature of the droplets based on the size, vertical velocity, initial temperature, and distance traveled by the droplets. The droplets reached temperatures between -5 and 0C. The deformation and breakup events were observed using a high-speed imaging system. A tracking software program processed the images captured and provided droplet deformation information along the path of the droplet as it approached the airfoil stagnation line. It was demonstrated that to compare the effects of water supercooling on droplet deformation, the slip velocity and the initial droplet velocity must be the same in the cases being compared. A case with a slip velocity of 40 m/s and an initial droplet velocity of 60 m/s was selected from both room temperature and supercooled droplet tests. In these cases, the deformation of the weakly supercooled and warm droplets did not present different trends when tested in room temperature and mild supercooling environments. The similar behavior for both environmental conditions indicates that water supercooling has no effect on particle deformation for the limited range of the weak supercooling of the droplets tested and the selected impact velocity.
Download or read book Handbook of Atomization and Sprays written by Nasser Ashgriz and published by Springer Science & Business Media. This book was released on 2011-02-18 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomization and sprays are used in a wide range of industries: mechanical, chemical, aerospace, and civil engineering; material science and metallurgy; food; pharmaceutical, forestry, environmental protection; medicine; agriculture; meteorology and others. Some specific applications are spray combustion in furnaces, gas turbines and rockets, spray drying and cooling, air conditioning, powdered metallurgy, spray painting and coating, inhalation therapy, and many others. The Handbook of Atomization and Sprays will bring together the fundamental and applied material from all fields into one comprehensive source. Subject areas included in the reference are droplets, theoretical models and numerical simulations, phase Doppler particle analysis, applications, devices and more.
Download or read book Numerical Modeling of Deformation Oscillation Spreading and Collision Characteristics of Droplets in an Electric Field written by Osameh Ghazian and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electric field induced flows, or electrohydrodynamics (EHD), have been promising in many fast-growing technologies, where droplet movement and deformation can be controlled to enhance heat transfer and mass transport. Several complex EHD problems existing in many applications were investigated in this thesis. Firstly, this thesis presents the results of numerical simulations of the deformation, oscillation and breakup of a weakly conducting droplet suspended in an ambient medium with higher conductivity. It is the first time that the deformation of such a droplet was investigated numerically in a 3D configuration. We have determined three types of behavior for the droplets, which are less conducting than ambient fluid: 1) oblate deformation (which can be predicted from the small perturbation theory), 2) oscillatory oblate-prolate deformation and 3) breakup of the droplet. Secondly, a numerical study of droplet oscillation placed on different hydrophobic surfaces under the effect of applied AC voltage including the effect of ambient gas was investigated. The presented algorithm could reproduce droplet oscillations on a surface considering different contact angles. It has been found that the resonance frequency of the water droplet depends on the surface property of the hydrophobic materials and the electrostatic force. Thirdly, a new design of an electrowetting mixer using the rotating electric field was proposed which offers a new method to effectively mix two droplets over a different range of AC frequencies. Two regimes were observed for droplet coalescence: 1) coalescence due to the high droplet deformation, 2) coalescence due to the interaction of electrically induced dipoles. Fourthly, the spreading and retraction control of millimetric water droplets impacting on dry surfaces have been investigated to examine the effect of the surface charge density and electric field intensity. The effect of the surface charge on the spreading of droplets placed gently on surfaces was investigated in the first part. It was found that the maximum spreading diameter increases with an increasing charge. In the second part, the impact of a droplet on a ground electrode was considered. It was also found that in order to keep the maximum diameter after the impact, less charge is needed for surfaces with lower contact angle. Finally, the interaction between two identical charged droplets was investigated numerically. The effects of the impact velocity, drop size ratio and electric charge on the behavior of the combined droplet were investigated. It was shown that two conducting droplets carrying charges of the same polarity under some conditions may be electrically attracted. The formation of charged daughter droplets has been investigated and it was found that the number of the satellite droplets after collision appears to increase with an increase in the droplet charge.
Download or read book Electrokinetic and Colloid Transport Phenomena written by Jacob H. Masliyah and published by John Wiley & Sons. This book was released on 2006-05-26 with total page 733 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new, definitive perspective of electrokinetic and colloid transport processes Responding to renewed interest in the subject of electrokinetics, Electrokinetic and Colloid Transport Phenomena is a timely overview of the latest research and applications in this field for both the beginner and the professional. An outgrowth of an earlier text (by coauthor Jacob Masliyah), this self-contained reference provides an up-to-date summary of the literature on electrokinetic and colloid transport phenomena as well as direct pedagogical insight into the development of the subject over the past several decades. A distinct departure from standard colloid science monographs, Electrokinetic and Colloid Transport Phenomena presents the most salient features of the theory in a simple and direct manner, allowing the book to serve as a stepping-stone for further learning and study. In addition, the book uniquely discusses numerical simulation of electrokinetic problems and demonstrates the use of commercial finite element software for solving these multiphysics problems. Among the topics covered are: * Mathematical preliminaries * Colloidal systems * Electrostatics and application of electrostatics * Electric double layer * Electroosmosis and streaming potential * Electrophoresis and sedimentation potential * London-Van der Waals forces and the DLVO theory * Coagulation and colloid deposition * Numerical simulation of electrokinetic phenomena * Applications of electrokinetic phenomena Because this thorough reference does not require advanced mathematical knowledge, it enables a graduate or a senior undergraduate student approaching the subject for the first time to easily interpret the theories. On the other hand, the application of relevant mathematical principles and the worked examples are extremely useful to established researchers and professionals involved in a wide range of areas, including electroosmosis, streaming potential, electrophoretic separations, industrial practices involving colloids and complex fluids, environmental remediation, suspensions, and microfluidic systems.
Download or read book Droplet deformation prediction with the Droplet Deformation and Breakup Model DDB written by Mario Vargas and published by . This book was released on 2012 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Droplet Deformation and Breakup in Coaxial Orifices During High pressure Homogenization written by Felix Johannes Preiss and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics of Deformation of Liquid Drops written by H. H. Chiu and published by . This book was released on 1969 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: A time dependent analysis is made of the deformation of an initially spherical drop moving in an unbound fluid at low Reynolds number. It is found that the excitation of a particular mode of deformation, including simple deformation, oscillation, and unstable deformation, depends on the Reynolds number, Weber number, the ratios of the two fluid densities and viscosities. The result of an analysis in the limit of vanishing voscosities shows that the droplet vibrates. The characteristic frequency obtained in the present analysis agrees with that previously obtained by H. Lamb. For large viscosities a limiting analysis indicates that a droplet deforms asymptotically to the equilibrium shape predicted by T.D. Taylor and A. Acrivos. The characteristic time of the deformation for ethyl alcohol droplets of 20 to 80 micrometers in diameter vary approximately from 0.001 sec to 0.005 sec. The effects of increasing temperature and pressure, free stream velocity and the droplet size are examined numerically for the deformation of ethyl alcohol drops. The unstable modes of deformation are likely to be excited at Reynolds number and Weber number both greater than unity. (Author).
Download or read book Droplet Deformation and Breakup written by Samuel Hall and published by . This book was released on 2008 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Particles Bubbles Drops written by Efstathios Michaelides and published by World Scientific. This book was released on 2006 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of multiphase flows has grown by leaps and bounds in the last thirty years and is now regarded as a major discipline. Engineering applications, products and processes with particles, bubbles and drops have consistently grown in number and importance. An increasing number of conferences, scientific fora and archived journals are dedicated to the dissemination of information on flow, heat and mass transfer of fluids with particles, bubbles and drops. Numerical computations and "thought experiments" have supplemented most physical experiments and a great deal of the product design and testing processes. The literature on computational fluid dynamics with particles, bubbles and drops has grown at an exponential rate, giving rise to new results, theories and better understanding of the transport processes with particles, bubbles and drops. This book captures and summarizes all these advances in a unified, succinct and pedagogical way. Contents: Fundamental Equations and Characteristics of Particles, Bubbles and Drops; Low Reynolds Number Flows; High Reynolds Number Flows; Non-Spherical Particles, Bubbles and Drops; Effects of Rotation, Shear and Boundaries; Effects of Turbulence; Electro-Kinetic, Thermo-Kinetic and Porosity Effects; Effects of Higher Concentration and Collisions; Molecular and Statistical Modeling; Numerical Methods-CFD. Key Features Summarizes the recent important results in the theory of transport processes of fluids with particles, bubbles and drops Presents the results in a unified and succinct way Contains more than 600 references where an interested reader may find details of the results Makes connections from all theories and results to physical and engineering applications Readership: Researchers, practicing engineers and physicists that deal with any aspects of Multiphase Flows. It will also be of interest to academics and researchers in the general fields of mechanical and chemical engineering.
Download or read book Measurement of Droplet Deformation in Simple Shear Flow with Zero Interfacial Tension written by Seb́astien Comas-Cardona and published by . This book was released on 2000 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
