On the mechanism of noncoalescence in a droplet cluster

Experimental data are presented, from which it follows that the mechanism of noncoalescence in a cluster of drops is not attributable to the electrostatic charging and the presence of surfactants. The Stokes force acting upon drops of the cluster in a convective plume amounts to a fraction of a percent of the drop weight. New effects are described, which provide evidence for a fast proper rotation of drops in the cluster. Estimates show that this rotation is explained in terms of the hypothesis of a thermocapillary nature of the noncoalescence phenomenon.