More on the Surface State of Expanding Champagne Bubbles Rising at Intermediate Reynolds and High Peclet Numbers

Abstract

Bubbles rising in a glass poured with carbonated beverage constitute a daily example of rising and expanding bubbles. By measuring both the drag coefficients and the Sherwood numbers of ascending champagne bubbles during their rise toward the free surface, we provided evidence that, contrary to bubbles of fixed or shrinking radii, expanding champagne bubbles experience a transient regime during ascent, where the bubble behavior progressively changes from that of a rigid sphere to that of a fluid sphere. The progressive gain of interfacial mobility during bubble ascent was interpreted as a dilution of the surface-active compounds on the rising bubble due to the continuous bubble growth. Time scales of bubble expansion and surfactant adsorption were estimated during the rise and found to be in quite good accordance with our experimental results at low Reynolds numbers.