Phase field modeling and computation of multi-component droplet evaporation

Abstract

Droplet evaporation is an interesting physical phenomenon and it has extensive applications in natural world or industrial fields. To investigate the evaporation of a single droplet and multiple droplets on a substrate, we develop novel and effective models based on phase field method. The interface of droplets can be implicitly captured by a specific level-set of order parameter (phase field function). The contact angle boundary condition derived from a wall free energy is adopted to reflect different wetting conditions. To reflect the effect of evaporation, we derive an evaporation term based on the relation between volume change and surface area. In each time step, the operator splitting based temporal discretization is adopted and all nonlinear terms are explicitly treated. Therefore, we can update each component in a step-by-step manner and the algorithm is efficient to implement. The proposed models and algorithms are validated by comparing the contact angle, spreading length, change of radius, and change of volume with analytical results. The effect of contact angle on a single droplet is investigated. Furthermore, the evaporations of multiple droplets under different contact angle conditions and pinning condition are simulated.