title: Droplet evaporation on a horizontal substrate under gravity field by mesoscopic modeling.
abstract: The evaporation of water drop deposited on a horizontal substrate is investigated using a lattice Boltzmann method (LBM) for multiphase flows with a large-density ratio. To account for the variation of evaporation flux distribution along the drop interface, a novel evaporation scheme is introduced into the LBM framework, and validated by comparison with experimental data. We aim at discovering the effect of gravity on the evaporating drop in detail, and various evaporation conditions are considered as well as different wetting properties of the substrates. An effective diameter is introduced as an indicator of the critical drop size under which gravity is negligible. Our results show that such critical diameter is much smaller than the capillary length, which has been widely accepted as the critical size in previous and current works. The critical diameter is found to be almost independent of the evaporation conditions and the surface wettability. A correlation between this critical diameter and the capillary length is also proposed for easy use in applications.
authors.affiliation: Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084, China.
authors.forename: Chiyu
authors.initials: C
authors.lastname: Xie
authors.affiliation: College of Engineering, Peking University, Beijing 100874, China.
authors.forename: Jianying
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GH, UK.
authors.forename: Volfango
authors.initials: V
authors.lastname: Bertola
authors.affiliation: Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084, China. Electronic address: mrwang@tsinghua.edu.cn.
authors.forename: Moran
authors.initials: M
authors.lastname: Wang
mesh_terms: D006112:Gravitation; D010316:Particle Size; D013499:Surface Properties; D014835:Volatilization; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water
keywords: Critical size; Drop evaporation; Gravity effect; Lattice Boltzmann method