Flow induced on a salt waterbody due to the impingement of a freshwater drop or a water source

• Published in: Mechanics research communications 2017-10, Vol.85, p.89-95
• Main Authors: Benouaguef, Islam, Amah, Edison, Musunuri, Naga, Blackmore, Denis, Fischer, Ian S., Singh, Pushpendra
• Format: Article
• Language: English
• Subjects: Drops; Particle image velocimetry and planar laser-induced fluorescence; Solutocapillary flow; Surface tension
• ISSN: 0093-6413; 1873-3972
• DOI: 10.1016/j.mechrescom.2017.08.004

The transient velocity field due to the impingement of a freshwater drop on a 35 ppt salt waterbody shown on a vertical plane passing through the center of the point of impact. [Display omitted] •When a freshwater drop impinges on a saltwater body there is a strong solutocapillary flow on the surface.•The solutocapillary extends over an area that is several orders of magnitude larger than the impact area.•The flow arises because when the drop mixes with saltwater the local salt concentration is reduced which gives rise to a surface tension gradient.•The presence of salt changes the characteristics of the flow that arises due to the impact of drops, and thus the state of mixing.•The results presented are of interest as they model the transport of sparingly soluble gases across air-water interface. The particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques are used to study the flow induced on the surface of a body of saltwater when a drop impinges on its surface or when a source is present on the surface. The measurements show that the impingement of a fresh water drop causes a strong axisymmetric solutocapillary flow about the vertical line passing through the center of impact. The fluid directly below the center of impact rises upward, and near the surface it moves away from the center of impact. The flow, which develops within a fraction of second after the impact, persists for several seconds. In comparison, when a freshwater drop falls on a body of freshwater, the flow induced on the surface is much weaker and persists for a relatively shorter duration of time and the volume of water circulated is two orders of magnitude smaller. Similarly, when a fresh water source is present on a body of saltwater there is a solutocapillary flow which on the surface is away from the source and below the surface is towards the source.