The paper deals with the investigation of generation of an average flow near a curved gas-liquid interface under the action of harmonic translational vibrations of small amplitude. Known mechanisms of flow generation near fluid interfaces (Schlichting and Dore mechanisms) vanish with the transition to the free surface and other mechanisms are related to the surface deformations (Longuet-Higgins mechanism). We found a new mechanism of flow generation near a curved free surface that is associated exclusively with the average surface curvature. This mechanism is insensitive to the pulsational deformations. This mechanism is investigated for the problem of a gaseous bubble suspended in an unbounded liquid, neglecting the viscosity and density of the gas. It is found that a steady flow arises around the bubble; besides deformation of the surface has no effect on the generation of this flow. The generation of an average flow near the curved liquid-liquid interface is also investigated. A liquid drop suspended in a vibrating liquid of different density is studied. It is shown that for comparable density and viscosity of liquids the dominating mechanism of average vorticity generation is similar to the Schlichting mechanism, whereas the effect of the interface curvature is less important. At low density of liquid inside the drop (and its small dynamic viscosity), all of the above mechanisms could contribute to the same order of magnitude. We demonstrate the interaction of these generation mechanismsconsidering a gaseous bubble suspended in an unbounded liquid.
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