Dynamics of an oil-coated bubble rising in a quiescent water medium,Physical Review Fluids

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Dynamics of an oil-coated bubble rising in a quiescent water medium
Physical Review Fluids ( IF 2.5 ) Pub Date : 2022-03-14 , DOI: 10.1103/physrevfluids.7.033603
Bingqiang Ji ₁ , Liu Hong ₁ , Jin-Tae Kim ₁ , Leonardo P. Chamorro _{1,

2,

3,

4} , Jie Feng _{1,

5}

Affiliation

We experimentally investigated the rising dynamics of oil-coated compound bubbles at various oil fractions in a quiescent water medium. Three-dimensional particle tracking velocimetry was used to characterize the trajectories of the bubbles, and particle image velocimetry was used for complementary flow characterization. Results show that the oil-coated bubbles undergo a zigzagging path with a steady oscillation pattern at comparatively low oil fractions. In contrast, damped oscillations occur at high oil fractions, which do not happen in clean gas bubbles. The oil coating changes the rising dynamics of the bubble mainly by adjusting the bubble surface boundary condition and effective density. A lightly coated bubble experiences a smaller shape deformation, similar drag coefficient, a larger frequency, and smaller amplitude in the path oscillation compared to a clean gas bubble. In addition, the increase of oil fraction results in reduced shape deformation and drag coefficient with a lower frequency and amplitude of the path oscillation. Estimation of the forces using a Frenet reference frame shows that the wake-induced lift and drag decreased with oil fraction, and became negligible for bubbles with damped oscillations. Overall, our work contributes to the fundamental understanding of the rising dynamics of oil-coated bubbles with various oil fractions and viscosities.

中文翻译：

油膜气泡在静止水介质中上升的动力学

我们通过实验研究了静态水介质中各种油馏分的油包覆复合气泡的上升动力学。三维粒子跟踪测速用于表征气泡的轨迹，粒子图像测速用于互补流动表征。结果表明，油包覆的气泡在相对较低的油分率下经历具有稳定振荡模式的锯齿形路径。相反，阻尼振荡发生在高油分率处，而在清洁气泡中不会发生。油涂层主要通过调节气泡表面边界条件和有效密度来改变气泡的上升动力学。薄涂的气泡会经历较小的形状变形，相似的阻力系数，较大的频率，与干净的气泡相比，路径振荡的幅度更小。此外，油分的增加导致形状变形和阻力系数减小，路径振荡的频率和幅度较低。使用 Frenet 参考系对力的估计表明，尾流引起的升力和阻力随着油分的增加而减小，并且对于具有阻尼振荡的气泡来说变得可以忽略不计。总体而言，我们的工作有助于从根本上理解具有各种油馏分和粘度的涂油气泡的上升动力学。使用 Frenet 参考系对力的估计表明，尾流引起的升力和阻力随着油分的增加而减小，并且对于具有阻尼振荡的气泡来说变得可以忽略不计。总体而言，我们的工作有助于从根本上理解具有各种油馏分和粘度的涂油气泡的上升动力学。使用 Frenet 参考系对力的估计表明，尾流引起的升力和阻力随着油分的增加而减小，并且对于具有阻尼振荡的气泡来说变得可以忽略不计。总体而言，我们的工作有助于从根本上理解具有各种油馏分和粘度的涂油气泡的上升动力学。

更新日期：2022-03-14

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