Measurement of Contaminated Single Drop by using Spatiotemporal Filter Velocimetry

Abstract

Experimental evaluation of surfactant concentration at a fluid-fluid interface is in great demand for understanding adsorption-desorption kinetics at the interface. In this study, spatiotemporal filter velocimetry (SFV) is applied to flow about a single drop of glycerol-water solution falling in a stagnant silicon oil under a contaminated condition. Distributions of surface tension and surfactant concentration along a longitude line of the interface are evaluated from the velocity distributions measured in the vicinity of the interface. The budget of the surfactant concentration is also evaluated from the measured data. The result shows that the evaluation of surfactant concentration using SFV is of great use in understanding adsorption-desorption kinetics at an interface in a contaminated system and for validation of numerical methods taking into account adsorption and desorption of surfactants.