Ling Hangjian, Ready John, O'Coin Daniel
Department of Mechanical Engineering, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA.
Biomimetics (Basel). 2025 Jun 7;10(6):382. doi: 10.3390/biomimetics10060382.
We experimentally studied the effect of a surfactant on bubble formation on a superhydrophobic surface (SHS). The bubble was created by injecting gas through an orifice on the SHS at a constant flow rate in the quasi-static regime. The surfactant, 1-pentanol, was mixed with water at concentration ranging from 0 to 0.08 mol/L, corresponding to surface tension ranging from 72 to 43 mN/m. We found that as increased, the bubble detachment volume () and maximum bubble base radius () decreased. For a low surfactant concentration, the static contact angle remained nearly constant, and and decreased due to lower surface tensions, following the scaling laws ~ and ~. The bubble shapes at different concentrations were self-similar. The bubble height, bubble base radius, radius at the bubble apex, and neck radius all scaled with the capillary length. For high surfactant concentrations, however, was greatly reduced, and and decreased due to the combined effects of reduced and smaller . Lastly, we found that the surfactant had a negligible impact on the forces acting on the bubble, except for reducing their magnitudes, and had little effect on the dynamics of bubble pinch-off, except for reducing the time and length scales. Overall, our results provide a better understanding of bubble formation on complex surfaces in complex liquids.
我们通过实验研究了表面活性剂对超疏水表面（SHS）上气泡形成的影响。在准静态状态下，通过以恒定流速通过超疏水表面上的孔口注入气体来产生气泡。将表面活性剂1-戊醇与水混合，浓度范围为0至0.08 mol/L，对应表面张力范围为72至43 mN/m。我们发现，随着浓度增加，气泡脱离体积（）和最大气泡底部半径（）减小。对于低表面活性剂浓度，静态接触角几乎保持不变，并且由于表面张力降低，和减小，遵循缩放定律和。不同浓度下的气泡形状是自相似的。气泡高度、气泡底部半径、气泡顶部半径和颈部半径均与毛细管长度成比例缩放。然而，对于高表面活性剂浓度，大大降低，并且由于降低和减小的综合作用，和减小。最后，我们发现表面活性剂对作用在气泡上的力的影响可以忽略不计，除了减小其大小外，对气泡 pinch-off 的动力学几乎没有影响，除了减小时间和长度尺度。总体而言，我们的结果有助于更好地理解复杂液体中复杂表面上的气泡形成。
