title: Growth and wetting of water droplet condensed between micron-sized particles and substrate.
abstract: We study heterogeneous condensation growth of water droplets on micron-sized particles resting on a level substrate. Through numerical simulations on equilibrium droplet profiles, we find multiple wetting states towards complete wetting of the particle. Specifically, a partially wetting droplet could undergo a spontaneous transition to complete wetting during condensation growth, for contact angles above a threshold minimum. In addition, we find a competitive wetting behavior between the particle and the substrate, and interestingly, a reversal of the wetting dependence on contact angles during late stages of droplet growth. Using quasi-steady assumption, we simulate a growing droplet under a constant condensation flux, and the results are in good agreement with our experimental observations. As a geometric approximation for particle clusters, we propose and validate a pancake model, and with it, show that a particle cluster has greater wetting tendency compared to a single particle. Together, our results indicate a strong interplay between contact angle, capillarity and geometry during condensation growth.
authors.affiliation: A*STAR Institute of High Performance Computing, 1 Fusionopolis Way, Connexis, 138632, Singapore.
authors.forename: Tran Si Bui
authors.initials: TS
authors.lastname: Quang
authors.affiliation: A*STAR Institute of High Performance Computing, 1 Fusionopolis Way, Connexis, 138632, Singapore.
authors.forename: Fong Yew
authors.initials: FY
authors.lastname: Leong
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore.
authors.forename: Hongjie
authors.initials: H
authors.lastname: An
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore.
authors.forename: Beng Hau
authors.initials: BH
authors.lastname: Tan
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore.
authors.forename: Claus-Dieter
authors.initials: CD
authors.lastname: Ohl