Dynamics of a drop at a liquid/solid interface in simple shear fields: A mesoscopic simulation study

Abstract

The dynamics of a surface-confined drop in a simple shear field has been studied, pursuing the dissipative particle dynamics (DPD) simulation approach. The shear field induces contact angle hysteresis in the drop, the degree of hysteresis increasing with the shear rate. At shear rates exceeding a critical value, the drop acquires the tendency to lift off the boundary, leading to its removal. In the equilibrium contact angle range, ϑ^e>120°, the drop preserves its integrity as it escapes from the boundary, whereas at lower contact angles the drop assumes a distinctly elongated shape prior to its removal, which develops “necks’' at subsequent times. The drop breaks up as the necks are ruptured upon thinning, with some fragments escaping into the bulk phase and some remaining at the surface. Under certain hydrodynamic conditions the moving drop sheds a trail of tiny droplets on the surface. The simulation results are in qualitative agreement with experimental studies on the corresponding systems published in the literature.

References

1. Cellular Automata and Modelling of Complex Physical Systems, ed. P. Manneville, N. Boccara, Y. G. Vichniac and R. Bidaux, Springer, Heidelberg, 1990.
2. F. W. J. Weig, P. V. Coveney and B. M. Boghosian, Phys. Rev. E: Stat. Phys. Plasmas Fluids Relat. Interdiscip. Top., 1997, 56, 6877.
3. A. J. Wagner and J. M. Yeomans, in Structure and Dynamics of Materials in the Mesoscopic Domain, Imperial College Press, London, 1999 in press.
4. S. I. Jury, P. Bladon, S. Krishna and M. E. Cates, in Structure and Dynamics of Materials in the Mesoscopic Domain, Imperial College Press, London, 1999, in press.
5. J. F. Olson and D. H. Rothman, J. Fluid Mech., 1997, 341, 343; A. Koponen, D. Kandhai, E. Hellen, M. Allava, A. Hoekstra, M. Kataja, K. Niskanen, P. Sloot and J. Timonen, Phys. Rev. Lett., 1998, 80, 716.
6. Y. Kong, C. W. Manke, W. G. Madden and A. G. Schlijper, J. Chem. Phys., 1997, 107, 592.
7. E. S. Boek, P. V. Coveney and H. N. W. Lekkerkerker, J. Phys. : Condens. Matter, 1996, 8, 9509; E. S. Boek, P. V. Coveney, H. N. W. Lekkerkerker and P. van der Schoot, Phys. Rev. E: Stat. Phys. Plasmas Fluids Relat. Interdiscip. Top., 1997, 55, 3124.
8. J. A. Barker, Lattice Theories of the Liquid State, Pergamon Press, Oxford, 1963.
9. D. d'Humieres, P. Lallemand and U. Frisch, Europhys. Lett., 1986, 2, 291.
10. G. R. McNamara and G. Zanetti, Phys. Rev. Lett., 1988, 61, 2332.
11. F. J. Higuera and H. Himenez, Europhys. Lett., 1989, 9, 663.
12. O. Behrand, Phys. Rev. E: Stat. Phys. Plasmas Fluids Relat. Interdiscip. Top., submitted; A. Lamura, G. Gonnella and J. M. Yeomans, Europhys. Lett., in press.
13. P. J. Hoogerbrugge and J. M. V. A. Koelman, Europhys. Lett., 1992, 19, 155; J. M. V. A. Koelman and P. J. Hoogerbrugge, Europhys. Lett., 1993, 21, 363.
14. Th. G. M. van de Ven, Colloidal Hydrodynamics, Academic Press, London, 1989.
15. P. Espanol and P. B. Warren, Europhys. Lett., 1995, 30, 191.
16. R. D. Groot and P. B. Warren, J. Chem. Phys., 1997, 107, 1423.
17. M. P. Allen and D. J. Tildesley, Computer Simulation of Liquids, Clarendon Press, Oxford, 1987.
18. J. H. Irving and J. G. Kirkwood, J. Chem. Phys., 1950, 18, 817.
19. G. Navascues and M. V. Berry, Mol. Phys., 1977, 34, 649.
20. M. J. P. Nijmeijer, C. Bruin, A. F. Bakker and J. M. J. van Leeuwen, Phys. Rev. A, 1990, 42, 6052.
21. N. K. Adam and G. Jessop, J. Chem. Soc., 1925, 127, 1863.
22. M. Mahe, M. Vignes-Adler, A. Rousseau, C. G. Jacquin and P. M. Adler, J. Colloid Interface Sci., 1988, 126, 314.
23. J. M. Yeomans, unpublished work.
24. M. Lal, J. N. Ruddock and N. A. Spenley, unpublished results.
25. B. J. Carroll, Colloids Surf. A, 1996, 114, 161; S. Basu, R. Kumar and K. S. Gandhi, Chem. Eng. Sci., 1997, 52, 2849.
26. D. Quere and E. Archer, Europhys. Lett., 1993, 24, 761.
27. R. D. Groot, unpublished results.