Interfacial mass transfer enhancement induced by bubble bouncing and shape oscillations

Bubble bouncing accompanied by shape oscillations enhances mass transfer by approximately 20%, compared with the predictions of the classical model dominated by convection for moving bubbles. This enhancement results from the circulation and the concentration boundary layer separation, both driven by relatively large-amplitude oscillations of low-order modes during bubble bouncing, which promote interface renewal, as revealed by the spatiotemporal evolution of the flow and concentration fields. Building on these findings, an extended Sherwood number formulation is proposed, which takes bubble bouncing with shape oscillations in the low-order mode into account.