  The aim of this paper is to experimentally and analytically study the
solutocapillary flow induced in a waterbody due to the presence of a solute
source on its surface and the mixing induced by this flow of the solutes and
gases dissolved at and near the surface into the waterbody. According to the
analytic solution, the induced flow is analogous to a doublet flow in the sense
that the flow is directed towards the source within a conical region with its
vertex at the source, and outside the conical region the flow moves away from
the source. The half cone angle for a negative source increases from $\sim$60
degrees with increasing source strength and Schmidt number reaching values
greater than 80 degrees. When the cone angle is large, the outflow is
restricted to a thin annular boundary layer region. These analytic results are
in agreement with our experimental data obtained by the PIV (Particle Image
Velocimetry) and PLIF (planar laser-induced fluorescence) techniques. As the
solute gradient at the surface gives rise to the force that drives the flow,
when the solute diffusion coefficient is reduced the flow becomes stronger and
persists longer because the solute gradient is maintained for a longer time and
distance. In experiments, the flow changes direction into the waterbody and the
surface flow stops when the solute induced surface tension gradient driving the
flow becomes comparable to the surface tension gradients that exist on the
surface due to temperature gradients.
