Author: Yu ZhengPublisher:
ISBN:
Category : Algorithms
Languages : en
Pages : 432
Book Description
Numerical Simulation of Droplet Deformation Using Spectral Element Method
Author: Yu ZhengNumerical Simulation of Droplet Deformation in Convective Flows
Author: Zheng-Tao DengNumerical Simulation of Droplet-deformation by a Level Set Approach with Surface Tension
Author: Roberto CroceNumerical Simulation of the Droplet-surface Impact Using InterFoam
Author: Fei GaoPublisher:
ISBN:
Category : Blood
Languages : en
Pages : 67
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.
Numerical Simulation of Time-dependent Droplet Deformation in an Electric Field
Author: Graeme M. SupeenePublisher:
ISBN:
Category : Drops
Languages : en
Pages : 298
Book Description
Numerical Simulation of Bubble and Droplet Deformation by a Level Set Approach with Surface Tension in Three Dimensions
Author: Roberto CroceA study of droplet deformation
Author: Hannah FryPublisher: Lulu.com
ISBN: 1291074317
Category : Science
Languages : en
Pages : 207
Book Description
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.
Numerical Modeling of Deformation, Oscillation, Spreading and Collision Characteristics of Droplets in an Electric Field
Author: Osameh GhazianPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
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.
A Numerical Simulation of Droplet Dynamics in Shear Layers
Author: Yuefa XiaoHandbook of Multiphase Polymer Systems
Author: Abderrahim BoudennePublisher: John Wiley & Sons
ISBN: 1119972884
Category : Technology & Engineering
Languages : en
Pages : 1322
Book Description
Multiphase polymeric systems include a wide range of materials such as composites, blends, alloys, gels, and interpenetrating polymer networks (IPNs). A one-stop reference on multiphase polymer systems, this book fully covers the preparation, properties, and applications of advanced multiphase systems from macro to nano scales. Edited by well-respected academics in the field of multiphase polymer systems, the book includes contributions from leading international experts. An essential resource for plastic and rubber technologists, filler specialists and researchers in fields studying thermal and electrical properties.