International Journal of Heat and Mass Transfer, Vol.95, 336-354, 2016
Lattice Boltzmann simulations of droplet impact onto surfaces with varying wettabilities
A liquid drop impacting on a solid substrate is simulated to evaluate the effect of inhomogeneities in the wetting characteristics of the surface. A high density ratio multiphase solver based on phase-field lattice Boltzmann formulation has been employed. Influence of receding contact angle and wettability gradient is investigated to analyse the coupled dynamics of the impacting droplet on the solid surface. Simulations indicate that the receding contact angle is a key wetting parameter to determine the final physical outcome of the impact process. Interplay between tangential velocity component and receding contact angle results in interesting dynamical behaviours in the evolution of the droplet shape for oblique impact scenarios. Substrate inhomogeneities in the form of wettability gradient is found to induce a directional behaviour to the motion of the impacting droplet. The droplet motion is characterised by intense recoiling along the upstream part of the droplet, followed by secondary spreading of the downstream contact line. (C) 2015 Elsevier Ltd. All rights reserved.
Keywords:Droplet impact;Lattice Boltzmann;Phase-field;Contact angle hysteresis;Wettability gradient;Oblique impact