Measuring interfacial tension using waves*

Interfacial tension measurement using parametrically excited interfacial waves is investigated. The method is assessed for applicability of acquiring low interfacial tension values between liquid-liquid layers. In the present experiments, an oil-water system is used. Low interfacial waves are generated by adding surfactant to the two-phase system to decrease the interfacial tension. Wavenumber of the excited system is obtained from shadowgraphs. To determine the interfacial tension value, a linear stability model is adapted. On basis of this model, it is concluded that there is a lower limit of interfacial tension value which can be measured using mechanically excited waves.