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" Axisymmetric Lattice Boltzmann Model of Droplet Impact on Solid Surfaces "
Dalgamoni, Hussein N.
Yong, Xin
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Latin Dissertation
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English
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| Record Number
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1052848
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TL51965
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| Main Entry
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Dalgamoni, Hussein N.
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| Title & Author
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Axisymmetric Lattice Boltzmann Model of Droplet Impact on Solid Surfaces\ Dalgamoni, Hussein N.Yong, Xin
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| College
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State University of New York at Binghamton
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| Date
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2019
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| Degree
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Ph.D.
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2019
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| Note
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111 p.
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| Abstract
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Droplet impact on solid surfaces is one of the fundamental phenomena encountered in a wide range of important engineering processes, such as spray cooling, inkjet-based additive manufacturing, bioassays and biosensors, as well as anti-icing and anti-fouling paints and coatings. In these applications, the dynamic behavior of the droplet as a result of its interaction with a solid surface plays a critical role in determining cooling efficiency, printing resolution, sensitivity, and coating performance. In this dissertation, an axisymmetric lattice Boltzmann method (LBM) was developed to model droplet impact on solid surfaces with various wettability for both flat and spherical surfaces. The method is based on the free-energy formulation of LBM to simulate binary incompressible flow with physical density and viscosity contrasts. The equation is recast in cylindrical coordinates for modeling the normal impact of a three-dimensional (3D) droplet in the no-splashing regime, in which the flow is axisymmetric. For the impact on flat surfaces, the distinct impact dynamics was probed based on droplet morphology and contact line behavior, which were quantitatively characterized by the spread factor, droplet aspect ratio, and dynamic contact angle. The simulations also resolved the detailed fluid velocity fields inside and outside the droplet, which provides additional insight into the morphological evolution and the mass/momentum transfer during impact. Explicit comparison between axisymmetric and conventional two-dimensional (2D) LBM highlights the importance of axisymmetric terms in governing equations for reproducing physical impact behavior. The axisymmetric LBM significantly reduces computational cost as compared with 3D LBMs and offers an effective means to study droplet impact in applicable conditions. For impacts on spherical solid surfaces, the axisymmetric LBM model was extended and modified for simulating the impact on curved substrates in the low Weber number regime. The results show that spherical target radii and surface wettability significantly affect the spreading and recoiling of droplet during impact. The simulations uncover five outcomes, which range from complete deposition to total rebound. A phase diagram was constructed and correlated with the total time that the droplet is in contact with the solid. Understanding droplet-solid interactions will aid in optimizing surface characteristics related to many scientific applications. For example, the total rebound of droplets from surfaces is essential in wet environments to preserve a dry surface condition and prevent corrosion. The impact dynamics also modulate the heat transfer between droplet and surface, which plays a vital role in spray cooling of high-power electronics and ice formation on airfoils. The axisymmetric LBM is a promising tool to uncover fundamental physics of droplet impact in applicable conditions and provides greater hydrodynamics insight inaccessible to experimental techniques. The finding will guide the surface structure design for controlling droplet hydrodynamics and the contact time during impact.
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| Descriptor
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Engineering
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Mechanical engineering
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Yong, Xin
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State University of New York at Binghamton
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