Wetting effects on the spreading of a liquid droplet colliding with a flat surface: Experiment and modeling

In this paper an experimental and theoretical study of the deformation of a spherical liquid droplet colliding with a flat surface is presented. The theoretical model accounts for the presence of inertia, viscous, gravitation, surface tension, and wetting effects, including the phenomenon of contact‐angle hysteresis. Experiments with impingement surfaces of different wettability were performed. The study showed that the maximum splat radius decreased as the value of the advancing contact angle increased. The effect of impact velocity on droplet spreading was more pronounced when the wetting was limited. The experimental results were compared to the numerical predictions in terms of droplet deformation, splat radius, and splat height. The theoretical model predicted well the deformation of the impacting droplet, not only in the spreading phase, but also during recoiling and oscillation. The wettability of the substrate upon which the droplet impinges was found to affect significantly all phases of the spre...

[1]  Francis H. Harlow,et al.  The Splash of a Liquid Drop , 1967 .

[2]  F. Harlow,et al.  Numerical Calculation of Time‐Dependent Viscous Incompressible Flow of Fluid with Free Surface , 1965 .

[3]  Mutsuto Kawahara,et al.  A finite element method for high Reynolds number viscous fluid flow using two step explicit scheme , 1983 .

[4]  Jiro Senda,et al.  Numerical Analysis of the Deformation Process of a Droplet Impinging upon a Wall , 1990 .

[5]  Takayuki Watanabe,et al.  Deformation and solidification of a droplet on a cold substrate , 1992 .

[6]  C. Avedisian,et al.  On the collision of a droplet with a solid surface , 1991, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.

[7]  J. Brackbill,et al.  A continuum method for modeling surface tension , 1992 .

[8]  Joel Koplik,et al.  Molecular dynamics of fluid flow at solid surfaces , 1989 .

[9]  F. Heslot,et al.  The Spreading of Layered Microdroplets , 1993 .

[10]  Roger H. Rangel,et al.  Numerical analysis of the deformation and solidification of a single droplet impinging onto a flat substrate , 1993 .

[11]  J. Madejski,et al.  Solidification of droplets on a cold surface , 1976 .

[12]  A. J. Markworth,et al.  Splat-quench solidification of freely falling liquid-metal drops by impact on a planar substrate , 1990 .

[13]  E. B. Dussan,et al.  LIQUIDS ON SOLID SURFACES: STATIC AND DYNAMIC CONTACT LINES , 1979 .

[14]  O. Hassager,et al.  An algorithm for the use of the Lagrangian specification in Newtonian fluid mechanics and applications to free-surface flow , 1985, Journal of Fluid Mechanics.

[15]  Gerardo Trapaga,et al.  Mathematical modeling of the isothermal impingement of liquid droplets in spraying processes , 1991 .

[16]  D. v..  On the ability of drops or bubbles to stick to non-horizontal surfaces of solids. Part 2. Small drops or bubbles having contact angles of arbitrary size , 1985, Journal of Fluid Mechanics.

[17]  D. Poulikakos,et al.  Solidification of Liquid Metal Droplets Impacting Sequentially on a Solid Surface , 1994 .

[18]  A. Adamson.  Physical chemistry of surfaces , 1960 .

[19]  Dimos Poulikakos,et al.  Modeling of the deformation of a liquid droplet impinging upon a flat surface , 1993 .

[20]  C. W. Hirt,et al.  Volume of fluid (VOF) method for the dynamics of free boundaries , 1981 .

[21]  Roger H. Rangel,et al.  Numerical simulation of substrate impact and freezing of droplets in plasma spray processes , 1993 .

[22]  P. Gennes.  Wetting: statics and dynamics , 1985 .

[23]  Robbins,et al.  Simulations of contact-line motion: Slip and the dynamic contact angle. , 1989, Physical review letters.

[24]  Dimos Poulikakos,et al.  Splat-quench solidification: estimating the maximum spreading of a droplet impacting a solid surface , 1993, Journal of Materials Science.

[25]  R. Redheffer,et al.  Mathematics of Physics and Modern Engineering , 1960 .

[26]  F. Heslot,et al.  Molecular layering in the spreading of wetting liquid drops , 1989, Nature.

[27]  L. Wachters,et al.  The heat transfer from a hot wall to impinging water drops in the spheroidal state , 1966 .

[28]  Dimos Poulikakos,et al.  Heat transfer aspects of splat-quench solidification: modelling and experiment , 1994 .