Wang, Geng;
(2023)
Lattice Boltzmann simulation of droplet dynamics.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Droplet dynamics have attracted significant research attention in recent years. Understanding the mechanisms of droplet impingement, collision, merging, and breakup could benefit a wide range of applications in industry, engineering and material science. In order to study the droplet dynamics in realistic applications, this thesis proposes improved multiphase lattice Boltzmann (LB) models to extend the range of accessible physical parameters. This is achieved by introducing improved schemes (e.g., the non-orthogonal moment set and the entropic lattice Boltzmann model) into a Unified lattice Boltzmann Model (ULBM) framework. Also, an extended combined pseudopotential (ECP) model is developed to simulate the multiphase flow of large density ratios and independently adjustable surface tension. The new LB models are extensively validated using experimental and theoretical results. Test results indicate that the proposed models can accurately reproduce the droplet dynamics for a wide range of operating parameters. Compared with previous multiphase LB models, the improved ULBM offers superior numerical stability and universality. The new multiphase LB models are then used to simulate droplet dynamics in realistic applications. Firstly, a droplet impact on a superhydrophobic mesh array is studied, focusing on the effect of liquid properties on droplet dynamics. Results indicate that the inertial effect dominates the spread stage of droplet impact. At later stages, the viscous drag and surface tension prevent the droplet spreading, resulting in different maximum spreading diameters. Then, a water droplet penetrating a micropillar array in a microchannel is investigated. A comprehensive parametric study is carried out by changing the droplet initial velocity, the micropillar array opening fraction, and the micropillar surface wettability. Finally, the ULBM framework is extended to simulate multiphase flows with phase change. Droplet bouncing on a heated porous plate is systematically investigated by varying the Weber numbers, the plate temperatures, and the plate configurations. The findings presented in this thesis may potentially facilitate the design of engineering devices.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Lattice Boltzmann simulation of droplet dynamics |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10166945 |
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