Dynamics of droplet coalescence in response to increasing hydrophobicity

作者：Graham Percival J^*; Farhangi Mehran M; Dolatabadi Ali

来源：Physics of Fluids, 2012, 24(11): 112105.

DOI：10.1063/1.4767513

• drops
• flow visualisation
• hydrophobicity
• numerical analysis
• two-phase flow
• wetting

Coalescence of a falling droplet with a sessile droplet on solid surface with various wettabilities is investigated by a combined experimental and numerical study. In the experiments, the droplet diameter, the impact velocity, and the distance between the impacting droplets were controlled. The evolution of surface shape during the coalescence of two droplets on various surfaces is captured using high speed imaging and compared with numerical results. A two-phase volume of fluid method is used to determine the dynamics of droplet coalescence, shape evaluation, and contact line movement. The spreading length of two coalescing droplets along their original centers is also predicted by the model and compared well with the experimental results. The effect of different parameters such as impact velocity, center to center distance, droplet size, and surface wettability on maximum spreading length are studied and compared to the experimental results. Finally, correlations are developed for predicting the maximum spreading length using both experimental and numerical results.

• 出版日期2012-11