Droplet deformation, oscillation and detachment on a vibrating plate by a controlled airflow

Abstract

AbstractIn this work, a detailed experimental study on the influence of fluid properties on the droplet behavior subjected to a shear flow and harmonic surface vibration is conducted. The experiments were executed in a rectangular channel and an acrylic channel wall was utilized to analyze the droplet wetting behavior. Both the effect of shearing mechanism induced by airflow and harmonic vibration induced by an electromagnetic shaker for droplet volumes in the range of 5−40 µl are studied here. Furthermore, the effect of fluid viscosities on the motion of droplets is analyzed for a wide range of water and glycerine mixture ratios. Experiments show that the critical bulk velocity at which the droplet movement begins is a function of fluid properties and droplet sizes. Increasing the droplet volume results in a decrease of the critical bulk velocity, while the droplet deformation increases. On the contrary, increasing the glycerine content of the liquid droplets results in an increase in both the critical bulk velocity and droplet deformation. The droplet movement can be categorized into three motion patterns based on experimental observations: (i) the droplet shape is largely retained with a small tail formation at the rear end, (ii) small droplets detach from the tail at rear end of the main droplet, (iii) the droplet deforms over its entire length resulting in forming of a film.