Application of free surface synthetic schlieren method in determining surface tension from a light floating object

Abstract Free surface synthetic schlieren (FS-SS) is a liquid surface topography visualization technique relying on apparent dot pattern displacement due to liquid surface deformation. It has gained attention in the fluid visualization field due to its relatively simple and inexpensive setup. One of the most powerful features of the FS-SS technique is the 3D topography of deformed liquid surface, in which submillimeter scale changes can be readily observed in great detail. The visualization of liquid meniscus at the solid interface is proposed in this study to calculate surface tension by equating the surface tension force with weight of light, floating object with circular geometry. It was found that surface tensions of liquids are much greater than anticipated, suggesting that the effect of buoyant force of displaced liquid due to deformed interface cannot be neglected. When the buoyant force is included, the calculated surface tension of liquids are within 10% of the reference values.