This paper presents an investigation of bubble mass transfer within a contraction microchannel using a volume of fluid (VOF)-based numerical method, aiming to understand the effects of liquid Reynolds number (Re_l) and capillary number (Ca_l) on mass transfer in such configuration. First, the applicability of the numerical method was validated with the cases of pure diffusion of dissolved gas from a stationary spherical bubble to the surrounding liquid and the transfer of dissolved gas from a free-rising bubble to the surrounding liquid. Then, the results show that, in low Re_l and Ca_l cases, Sherwood number (Sh) shows an increase–decrease trend with a pronounced peak, as the bubble passes through the contraction, which is referred to as the contraction-induced mass transfer peak effect. As Re_l and Ca_l increase, this peak effect gradually weakens. Finally, a map used to describe the critical condition for such peak effect is proposed.

中文翻译：

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收缩构型微通道中气泡的传质行为─数值研究


本文采用基于流体体积 (VOF) 的数值方法研究收缩微通道内的气泡传质，旨在了解液体雷诺数 (Re) 和毛细管数 (Ca) 对这种结构中传质的影响。首先，通过溶解气体从静止球形气泡纯扩散到周围液体和溶解气体从自由上升气泡转移到周围液体的情况验证了数值方法的适用性。然后，结果表明，在低Re和Ca情况下，随着气泡经过收缩，舍伍德数（Sh）呈现增加-减少趋势，并出现明显的峰值，这被称为收缩引起的传质峰影响。随着Re和Ca的增加，这种峰值效应逐渐减弱。最后，提出了用于描述这种峰值效应的临界条件的图。