The influence of surface tension gradients on drop coalescence

François Blanchette (1) , Laura Messio (2) , John W. M. Bush (3)

1 School of Natural Sciences
2 LPTMC - Laboratoire de Physique Théorique de la Matière Condensée
3 Department of Mathematics [MIT]

We present the results of a combined experimental and numerical investigation of the coalescence of a drop with a liquid reservoir of a miscible but distinct fluid. Particular attention is given to elucidating the influence on the coalescence process of a surface tension difference between drop and reservoir. Drops are gently deposited on the surface of the reservoir, and so coalesce with negligible initial vertical velocity. Depending on the drop size and reservoir composition, partial or total coalescence may occur. Three distinct regimes, depending on the reservoir to drop surface tension ratio, Rσ, are identified and delineated through both experiments and numerics. If Rσ<0.42, droplets are ejected from the top of the drop, while satellite droplets are left in its wake. For 0.42<=Rσ<0.93, only total coalescence is observed. When Rσ>=0.93, partial coalescence is increasingly favored as the reservoir's surface tension increases.

Mots clés: Drops and bubbles

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

François Blanchette, Laura Messio, John W. M. Bush. The influence of surface tension gradients on drop coalescence. Physics of Fluids, 2009, 21, 072107 (11 p.). ⟨10.1063/1.3177339⟩. ⟨hal-00646105⟩