Coalescence-induced jumping and condensation of argon nanodroplets in the Cassie or the Wenzel state on nanopillar-arrayed surfaces
Journal
Colloids and Surfaces A: Physicochemical and Engineering Aspects
Journal Volume
628
Date Issued
2021
Author(s)
Abstract
Coalescence-induced droplet jumping on pillar-arrayed surfaces has received extensive attention. The pillar size and distribution affect the coalescence and jumping of droplets with unclear mechanisms. For the first time, this study performs molecular dynamics (MD) simulations to reveal the effects of initial wetting states on jumping and associated condensation processes at various intrinsic contact angles (θY), solid fractions (f), and roughness factors (r). The results show that although jumping and its velocity strongly depend on θY, f, and r, as reported in previous studies, the underlying mechanism to determine whether jumping occurs is the initial wetting state of coalescing droplets on textured surfaces. With the same θY and f, when the droplets are initially in the Cassie state, jumping can take place, whereas it may be hindered when the droplets are in the Wenzel state. The jumping velocity shows a decreasing trend for Cassie droplets when increasing f, but the reverse is true for Wenzel droplets. Additionally, it is found that the wetting state of a condensed droplet would transition from the Wenzel state to the Cassie state when the solid fraction increases but the pillar height and intrinsic wettability remain unchanged. ? 2021 Elsevier B.V.
Subjects
Coalescence
Condensation
Jumping
Pillar-arrayed surface
Wetting state
Argon
Drops
Flocculation
Molecular dynamics
Nanopillars
Textures
Wetting
Cassie state
Condensation process
Dynamics simulation
Nano-droplets
NanoPillar
Solids fraction
Wenzel state
SDGs
Type
journal article