Measurements of interfacial properties with the axisymmetric bubble-shape analysis technique: effects of vibrations

Abstract

We studied the effects of perturbation by vibration on the surface tension and surface area data obtained with the bubble-profile fitting method, using a typical laboratory apparatus. Examining an air bubble issuing downwards from a capillary tip, inside a vessel containing water, we report experimental observations about the effect of multifrequency vibrations on the bubble profile, either in the non-resonance or in the resonance condition, for some normal oscillation modes of the bubble and of the liquid body. Experimental results are given with regard to multifrequency-vibration disturbances on determination of the static surface tension of the liquid and the geometrical properties of the bubble, as a function of acceleration amplitude of vibration. Also, illustrative experimental observations are presented of the dynamic surface tension response to a surface area change, for a surfactant solution, under the action of vibration motion. In the frequency–acceleration plane, we show negligible effects on surface data in the 0–100 Hz and 0–5m g domain, for the geometrical configuration examined and the overall experimental system. The tolerability limit appears at 10m g acceleration, where excitation of the bubble resonance oscillation may occur with significant amplitude. The conclusions are also useful for estimation of the vibration effects in different configurations.