Lattice Boltzmann investigation of droplets impact behaviors onto a solid substrate

The numerical study of droplets impact behaviors onto a solid substrate is performed in this work. With a given impact velocity, one or two two-dimensional droplets subsequently interact with the substrate. During the process of droplet development on the substrate, the gravity is taken into account. To conduct numerical simulations, a hybrid method is adopted, in which the flow field is solved by using the lattice Boltzmann method and the interface is captured by solving the Cahn-Hilliard equation directly. The effects of Bond number (Bo, ratio of gravity to surface tension of droplet), Weber number (We, ratio of inertial force to surface tension) and droplet arrangement on the dynamic behaviors of droplets impact are systematically investigated. After a single droplet impact, a higher Weber number can lead to a longer contact length. In addition, the occurrence of bubble entrapment is determined by the Bond number. On the other hand, in the case of two droplets impact, several segments accompanying with their detachment from the surface are observed when two identical droplets are initially placed close to each other. Moreover, sparse segments, which are attributed to the oblique jet, are produced when two droplets have different sizes. (C) 2015 Elsevier B.V. All rights reserved.