The low surface Péclet number regime for surfactant-laden viscous droplets: Influence of surfactant concentration, interfacial slip effects and cross migration
| Autor: | Christian Rohde, V. Sharanya, G. P. Raja Sekhar |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Fluid Flow and Transfer Processes
Materials science Mechanical Engineering Drop (liquid) General Physics and Astronomy Marangoni number Péclet number Mechanics Stokes flow Hagen–Poiseuille equation 01 natural sciences 010305 fluids & plasmas Condensed Matter::Soft Condensed Matter Physics::Fluid Dynamics symbols.namesake Drag 0103 physical sciences symbols Potential flow 010306 general physics Couette flow |
| Zdroj: | International Journal of Multiphase Flow. 107:82-103 |
| ISSN: | 0301-9322 |
| DOI: | 10.1016/j.ijmultiphaseflow.2018.05.008 |
| Popis: | We consider the motion of a viscous drop in an arbitrary unsteady Stokes flow such that the surface of the drop is fully covered with a stagnant surfactant layer. In particular the regime of low surface Peclet number is analyzed and we account for the effect interfacial slip on the overall behavior of the flow field. The hydrodynamic problem is solved by the solenoidal decomposition method and the drag force is computed in terms of Faxen’s laws, using a perturbation ansatz in powers of the surface Peclet number. The surface equation of the deformed sphere has been determined by an iterative method up to the first order approximation. Analytical expressions for the migration velocity of the drop are likewise given. Based on this analysis we can completely characterize various flow situations including a given ambient flow as uniform flow, Couette flow and Poiseuille flow. Moreover, we find out that a surfactant-induced cross-stream migration of the drop occurs towards the center-line in both, Couette and Poiseuille flow cases. The variation of the drag force and the migration velocity is computed for different parameters such as the Peclet number and the Marangoni number. Finally, the theoretical findings are validated on with available experimental data. |
| Databáze: | OpenAIRE |
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