Inertial coalescence of droplets on a partially wetting substrate

Yi Sui (1) , Marco Maglio (2) , Peter D. M. Spelt (3) , Dominique Legendre (2) , Hang Ding (4)

1 SEMS - School of Engineering and Materials Science [London]
2 IMFT - Institut de mécanique des fluides de Toulouse
3 LMFA - Laboratoire de Mecanique des Fluides et d'Acoustique
4 Department of modern mechanics (Hefei, Chine)

We consider the growth rate of the height of the connecting bridge in rapid surface-tension-driven coalescence of two identical droplets attached on a partially wetting substrate. For a wide range of contact angle values, the height of the bridge grows with time following a power law with a universal exponent of 2/3, up to a threshold time, beyond which a 1/2 exponent results, that is known for coalescence of freely-suspended droplets. In a narrow range of contact angle values close to 90◦, this threshold time rapidly vanishes and a 1/2 exponent results for a 90◦ contact angle. The argument is confirmed by three-dimensional numerical simulations based on a diffuse interface method with adaptive mesh refinement and a volume-of-fluid method.

Mots clés: Drop; Coalescence; Substrate; Simulation

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Yi Sui, Marco Maglio, Peter D. M. Spelt, Dominique Legendre, Hang Ding. Inertial coalescence of droplets on a partially wetting substrate. Physics of Fluids, 2013, 25, pp.1-7, 101701. ⟨10.1063/1.4824108⟩. ⟨hal-00919847⟩