Control of droplet evaporation on smooth chemical patterns

Michael Ewetola, Rodrigo Ledesma Aguilar, Marc Pradas

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate the evaporation of a two-dimensional droplet on a solid surface. The solid is flat but with smooth chemical variations that lead to a space-dependent local contact angle. We perform a detailed bifurcation analysis of the equilibrium properties of the droplet as its size is changed, observing the emergence of a hierarchy of bifurcations that strongly depends on the particular underlying chemical pattern. Symmetric and periodic patterns lead to a sequence of pitchfork and saddle-node bifurcations that make stable solutions become saddle nodes. Under dynamic conditions, this change in stability suggests that any perturbation in the system can make the droplet shift laterally while relaxing to the nearest stable point, as is confirmed by numerical computations of the Cahn-Hilliard and Navier-Stokes system of equations. We also consider patterns with an amplitude gradient that creates a set of disconnected stable branches in the solution space, leading to a continuous change of the droplet's location upon evaporation.
Original languageEnglish
Article number033904
JournalPhysical Review Fluids
Volume6
DOIs
Publication statusPublished - 22 Mar 2021

Keywords

  • Contact line dynamics
  • Evaporation
  • Surface tension effects
  • Wetting
  • Drop & bubble phenomena
  • Navier-Stokes equation
  • Fluid Dynamics

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