Evidence of oscillatory convection inside an evaporating multicomponent droplet in a closed chamber

Visualization of an evaporating binary (ethanol-water) droplet reveals presence of oscillatory internal circulation. The visualization is done by using a laser scattering technique. The oscillatory circulation possibly results from the opposing effect of solutal and thermal Marangoni convection as proposed in some earlier theoretical works. The frequency of this oscillation is measured and the variation of this frequency with the initial concentration of the volatile component (ethanol) is reported. © 2012 Elsevier Inc.