0100493554

open access

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Drag and interfacial vorticity of spherical bubble contaminated with soluble surfactant

English (英語)

International Journal of Multiphase Flow

187

105173

Elsevier

2025-06

2025-03-11

Numerical simulations of spherical bubbles contaminated with soluble surfactant were carried out to investigate the surfactant effects on the drag coefficient, CD, and the interfacial vorticity, ω, produced at the bubble interface. The different surface contamination regimes are considered in both the diffusion-dominant case and advection-dominant case, for different ambient contamination conditions controlled by varying the Marangoni, Langmuir and Hatta numbers, Ma, La and Ha. The combinations, ΠM=LaMa and ΠH=Ha/La, of the dimensionless groups were found to play dominant roles in the surfactant effects on CD and ω in both cases. Four different regimes for the dependence of the drag force and vorticity distribution as a function of the above dimensionless group were identified. In the diffusion-dominant case the vorticity is well correlated with a weighting average for those of clean and fully-contaminated bubbles, and a linear relation between CD and the maximum vorticity holds as in the case with clean bubbles. The characteristics of CD in the advection-dominant case are more complicated, but they have been classified into four regimes in terms of ΠM and ΠH. A simple correlation of the stagnant-cap angle expressed in terms of ΠM was also obtained. This study thus revealed the surfactant effects on CD and ω and the drag-vorticity relations in detail at the first time for the different regimes of surface contamination.

Drag-vorticity relation

学術雑誌論文

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