Coalescence of two drops on partially wettable substrates.

The present work contains the results of the experiments with two tiny drops on partially wettable substrates with contact angles of 10°, 24°, 27°, and 56°, which coalesce in the regime entirely dominated by viscous forces. Both side and bottom views are examined. The results for these three-dimensional coalescence flows are compared with scaling laws and the numerical two-dimensional model developed in the present work.