A numerical study on the interaction of two spherical drops in thermocapillary migration in microgravity is presented. Unequal drop sizes in the axisymmetric model lead to strong drop interaction if the leading drop is smaller. The effect of the ratio of the two drop radii, their initial distance apart, and non-dimensional numbers on the interaction is studied in the case of non-merging drops in detail. The Marangoni number adopted in this paper is fairly large (around 100) so as to reveal the phenomena of real flows. As a result, the heat wake behind the leading drop plays an important role in drop interaction, and obviously different final drop distances and transient migration processes are observed for various sets of non-dimensional numbers. The influence of drop deformation on drop interaction is also investigated for relatively large capillary number (up to 0.2). Finally, some simulations are performed to explain the phenomena of drop interaction in previous experiments, and some suggestions for future experiments are also provided.
| http://dx.doi.org/10.1017/jfm.2015.10 |
Yin ZH,Li QH. Thermocapillary migration and interaction of drops: two non-merging drops in an aligned arrangement[J]. JOURNAL OF FLUID MECHANICS,2015-02,766(3):436-467.
This project is supported by NSF of China (Contracts No. G11472283 and G11172308). The authors wish to thank Professor Y. P. Zhang for many valuable discussions and for her critical reading of the manuscript. Z.Y. thanks Professor J. C. Xie, Dr W. T. Bi, and Professor R. S. Subramanian for their helpful discussions on physical problems and Dr Q. Kang and Dr L. Duan for discussing some of their experimental details. Q. L. thanks Mr K. Y. Lou, Dr L. Chang and Dr K. Yang for their technical and scientific support. Professor W. R. Hu provides invaluable support for this work. The authors are indebted to the three anonymous referees for their extremely detailed advice and drawing the authors' attention to more previous works in this field.