Auto-oscillations of surface tension: experiments with octanol and hexanol and numerical simulation of the system dynamics

Auto-oscillations of the surface tension which are a new manifestation of the instability by the mass transfer in a two-component system, are considered. Experimental results for droplets of octanol and hexanol under a free water surface are presented as well as a theoretical explanation of the phenomena observed. Comparison of experimental results with those obtained by numerical simulation shows that the proposed model provides an adequate description of the system behaviour for middle-chain alcohols like octanol. The system behaviour is determined by matching between diffusion and Marangoni convection. For shorter chain alcohols like hexanol the buoyancy effect should be taken into account.