Experimental and numerical study of droplet formation with Marangoni instability

The Marangoni effect produces some complex phenomena during droplet formation and has an important influence on the mass transfer state. In this paper, the droplet formation process of toluene/acetone/water droplet extraction system accompanied by Marangoni instability was numerically simulated, and the actual mass transfer states of droplets were photographed using schlieren imaging technology. The results reveal that: suspended droplets may have mass transfer states such as diffusion layer, natural convection, jet and turbulence, and the Marangoni instability causes the droplets to jet solute intermittently. Compared to droplets with constant surface tension, the Marangoni effect increases the mass transfer rate during droplet formation, and the Marangoni stress generates Marangoni convection at the interface, whose mutual annexation with the internal circulation leads to droplet oscillations. The Marangoni effect also causes pulsations in droplet vorticity, increasing the solute concentration exacerbates the vortex disorder, while increasing the injection rate may suppress the pulsations, which are physically dependent on the relative advantage of droplet internal circulation over Marangoni convection.