Article pubs.acs.org/Langmuir
Lattice Boltzmann Modeling of Droplet Condensation on Superhydrophobic Nanoarrays Qingyu Zhang,† Dongke Sun,‡ Youfa Zhang,*,† and Mingfang Zhu*,† †
Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China ‡ School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China S Supporting Information *
ABSTRACT: Droplet nucleation and growth on superhydrophobic nanoarrays is simulated by employing a multiphase, multicomponent lattice Boltzmann (LB) model. Three typical preferential nucleation modes of condensate droplets are observed through LB simulations with various geometrical parameters of nanoarrays, which are found to influence the wetting properties of nanostructured surfaces significantly. The droplets nucleated at the top of posts (top nucleation) or in the upside interpost space of nanoarrays (side nucleation) will generate a nonwetting Cassie state, while the ones nucleated at the bottom corners between the posts of nanoarrays (bottom nucleation) produce a wetting Wenzel state. The simulated time evolutions of droplet pressures at different locations are analyzed, which offers insight into the underlying physics governing the motion of droplets growing from different nucleation modes. It is demonstrated that the nanostructures with taller posts and a high ratio of post height to interpost space (H/S) are beneficial to produce the top- and side-nucleation modes. The simulated wetting states of condensate droplets on the nanostructures, having various geometrical configurations, compare reasonably well with experimental observations. The established relationship between the geometrical parameters of nanoarrays and the preferential nucleation modes of condensate droplets provides guidance for the design of nanoarrays with desirable anticondensation superhydrophobic properties.
1. INTRODUCTION When a liquid droplet deposited on a solid surface displays the Cassie state with an apparent contact angle larger than 150° and a small roll-off angle (
