Marangoni effects on oil droplets rising in a stratified fluid

When a droplet of lower density rises through a stratified ambient fluid, it will often get trapped in regions of high density gradient. This phenomena is observed in many environments, for example, during smoke plume dispersal in thermal inversions or trapping of oil plumes in ocean density gradients due to varying salt concentration and temperature. Such changes may also affect interfacial tension, in which case Marangoni effects will produce additional flows which affect the droplet trapping. Recent studies indicate that these effects may be significant in some regimes. We conducted experiments at the intermediate Reynolds regime to quantify how interfacial tension gradients affect the motion of a single oil droplet rising through a stratified ambient fluid.