Skip to main content
×
Home

Impact of ultra-viscous drops: air-film gliding and extreme wetting

  • K. Langley (a1), E. Q. Li (a1) and S. T. Thoroddsen (a1)
Abstract

A drop impacting on a solid surface must push away the intervening gas layer before making contact. This entails a large lubricating air pressure which can deform the bottom of the drop, thus entrapping a bubble under its centre. For a millimetric water drop, the viscous-dominated flow in the thin air layer counteracts the inertia of the drop liquid. For highly viscous drops the viscous stresses within the liquid also affect the interplay between the drop and the gas. Here the drop also forms a central dimple, but its outer edge is surrounded by an extended thin air film, without contacting the solid. This is in sharp contrast with impacts of lower-viscosity drops where a kink in the drop surface forms at the edge of the central disc and makes a circular contact with the solid. Larger drop viscosities make the central air dimple thinner. The thin outer air film subsequently ruptures at numerous random locations around the periphery, when it reaches below 150 nm thickness. This thickness we measure using high-speed two-colour interferometry. The wetted circular contacts expand rapidly, at orders of magnitude larger velocities than would be predicted by a capillary–viscous balance. The spreading velocity of the wetting spots is ${\sim}0.4~\text{m}~\text{s}^{-1}$ independent of the liquid viscosity. This may suggest enhanced slip of the contact line, assisted by rarefied-gas effects, or van der Waals forces in what we call extreme wetting. Myriads of micro-bubbles are captured between the local wetting spots.

Copyright
Corresponding author
Email address for correspondence: sigurdur.thoroddsen@kaust.edu.sa
References
Hide All
Andrews M. K. & Harris P. D. 1995 Damping and gas viscosity measurements using a microstructure. Sensors Actuators A 49, 103108.
Baldessari F., Homsy G. M. & Leal L. G. 2007 Linear stability of a draining film squeezed between two approaching droplets. J. Colloid Interface Sci. 307, 188202.
Blake T. D., Fernandez-Toledano J.-C., Doyen G. & De Coninck J. 2015 Forced wetting and hydrodynamic assist. Phys. Fluids 27, 112101.
Bouwhuis W., van der Veen R. C. A., Tran T., Keij D. L., Winkels K. G., Peters I. R., van der Meer D., Sun C., Snoeijer J. H. & Lohse D. 2012 Maximal air bubble entrainment at liquid-drop impact. Phys. Rev. Lett. 109, 264501.
Carlson A., Bellani G & Amberg G. 2012 Universality in dynamic wetting dominated by contact-line friction. Phys. Rev. E 85, 045302(R).
Chan D. Y. C., Klaseboer E. & Manica R. 2011 Film drainage and coalescence between deformable drops and bubbles. Soft Matt. 7, 22352264.
Chan T. S., Srivastava A., Marchand A., Andreotti B., Biferale L., Toschi F. & Snoeijer J. H. 2013 Hydrodynamics of air entrainment by moving contact lines. Phys. Fluids 25, 074105.
Crooks J., Marsh B., Turchetta R., Taylor K., Chan W., Lahav A. & Fenigstein A. 2013 Kirana: a solid-state megapixel uCMOS image sensor for ultrahigh speed imaging. Proc. SPIE 8659, 865903.
Driscoll M. M. & Nagel S. R. 2011 Ultrafast interference imaging of air in splashing dynamics. Phys. Rev. Lett. 107, 154502.
Driscoll M. M., Stevens C. S. & Nagel S. R. 2010 Thin film formation during splashing of viscous liquids. Phys. Rev. E 82, 036302.
Duchemin L. & Josserand C. 2011 Curvature singularity and film-skating during drop impact. Phys. Fluids 23, 091701.
Eddi A., Winkels K. G. & Snoeijer J. H. 2013 Short time dynamics of viscous drop spreading. Phys. Fluids 25, 013102.
Frostad J. M., Walter J. & Leal L. G. 2013 A scaling relation for the capillary-pressure driven drainage of thin films. Phys. Fluids 25, 052108.
Hicks P. D., Ermanyuk E. V., Gavrilov N. V. & Purvis R. 2012 Air trapping at impact of a rigid sphere onto a liquid. J. Fluid Mech. 695, 310320.
Hicks P. D. & Purvis R. 2010 Air cushioning and bubble entrapment in three-dimensional droplet impacts. J. Fluid Mech. 649, 135163.
Hicks P. D. & Purvis R. 2013 Liquid–solid impacts with compressible gas cushioning. J. Fluid Mech. 735, 120149.
Jennings S. G. 1988 The mean free path in air. J. Aero. Sci. 19, 159166.
Josserand C. & Thoroddsen S. T. 2016 Drop impact on a solid surface. Annu. Rev. Fluid Mech. 48, 365391.
Kaur S. & Leal L. G. 2009 Three-dimensional stability of a thin film between two approaching drops. Phys. Fluids 21, 072101.
Klaseboer E., Manica R. & Chan D. Y. C. 2014 Universal behavior of the initial stage of drop impact. Phys. Rev. Lett. 113, 194501.
Kolinski J. M., Mahadevan L. & Rubinstein S. M. 2014 Drops can bounce from perfectly hydrophilic surfaces. Eur. Phys. Lett. 108, 24001.
Kolinski J. M., Rubinstein S. M., Mandre S., Brenner M. P., Weitz D. A. & Mahadevan L. 2012 Skating on a film of air: drops impacting on a surface. Phys. Rev. Lett. 108, 074503.
Korobkin A. A., Ellis A. S. & Smith F. T. 2008 Trapping of air in impact between a body and shallow water. J. Fluid Mech. 611, 365394.
Lee J. S., Weon B. M., Je J. H. & Fezzaa K. 2012 How does an air film evolve into a bubble during drop impact? Phys. Rev. Lett. 109, 204501.
Li E. Q. & Thoroddsen S. T. 2015 Time-resolved imaging of a compressible air disc under a drop impacting on a solid surface. J. Fluid Mech. 780, 636648.
Li E. Q., Vakarelski I. U. & Thoroddsen S. T. 2015 Probing the nanoscale: the first contact of an impacting drop. J. Fluid Mech. 785, R2.
Liu Y., Tan P. & Xu L. 2013 Compressible air entrapment in high-speed drop impacts on solid surfaces. J. Fluid Mech. 716, R9.
Mandre S. & Brenner M. P. 2012 The mechanism of a splash on a dry solid surface. J. Fluid Mech. 690, 148172.
Mandre S., Mani M. & Brenner M. P. 2009 Precursors to splashing of liquid droplets on a solid surface. Phys. Rev. Lett. 102, 134502.
Mani M., Mandre S. & Brenner M. P. 2010 Events before droplet splashing on a solid surface. J. Fluid Mech. 647, 163185.
Mansoor M. M., Marston J. O., Uddin J., Christopher G., Zhang Z. & Thoroddsen S. T. 2016 Cavitation structures formed during the collision of a sphere with an ultra-viscous wetted surface. J. Fluid Mech. 796, 473515.
Marchand A., Chan T. S., Snoeijer J. H. & Andreotti B. 2012 Air entrainment by contact lines of a solid plate plunged into a viscous fluid. Phys. Rev. Lett. 108, 204501.
Palacios J., Hernández J., Gómez P., Zanzi C. & López J. 2012 On the impact of viscous drops onto dry smooth surfaces. Exp. Fluids 52, 14491463.
Riboux G. & Gordillo J. M. 2014 Experiments of drops impacting a smooth solid surface: a model of the critical, impact speed for drop splashing. Phys. Rev. Lett. 113, 024507.
de Ruiter J., Lagraauw R., van den Ende D & Mugele F. 2015 Wettability-independent bouncing on flat surfaces mediated by thin air films. Nat. Phys. 11, 4853.
de Ruiter J., Mugele F. & van den Ende D. 2015 Air cushioning in droplet impact. II: Experimental characterization of the air film evolution. Phys. Fluids 27, 012104.
de Ruiter J., Oh J. M., van den Ende D & Mugele F. 2012 Dynamics of collapse of air films in drop impact. Phys. Rev. Lett. 108, 074505.
Smith F. T., Li L. & Wu G. X. 2003 Air cushioning with a lubrication/inviscid balance. J. Fluid Mech. 482, 291318.
Snoeijer J. H. & Andreotti B. 2013 Moving contact lines: scales, regimes, and dynamical transitions. Annu. Rev. Fluid Mech. 45, 269292.
Sprittles J. E. & Shikhmurzaev Y. D. 2014a The coalesence of liquid drops in a viscous fluid: interface formation model. J. Fluid Mech. 751, 480499.
Sprittles J. E. & Shikhmurzaev Y. D. 2014b A parametric study of the coalescence of liquid drops in a viscous gas. J. Fluid Mech. 753, 279306.
Stevens C. S., Latka A. & Nagel S. N. 2014 Comparison of splashing in high- and low-viscosity liquids. Phys. Rev. E 89, 063006.
Thoroddsen S. T., Etoh T. G., Takehara K., Ootsuka N. & Hatsuki Y. 2005 The air-bubble entrapped under a drop impacting on a solid surface. J. Fluid Mech. 545, 203212.
Thoroddsen S. T., Takehara K. & Etoh T. G. 2010 Bubble entrapment through topological change. Phys. Fluids 22, 051701.
Thoroddsen S. T., Thoraval M.-J., Takehara K. & Etoh T. G. 2010 Micro-bubble morphologies following drop impacts onto a pool surface. J. Fluid Mech. 708, 469479.
van der Veen R. C. A., Tran T., Lohse D. & Sun C. 2012 Direct measurements of air layer profiles under impacting droplets using high-speed color interferometry. Phys. Rev. E 85, 026315.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
  • URL: /core/journals/journal-of-fluid-mechanics
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×
MathJax

Keywords:

Type Description Title
VIDEO
Movies

Langley et al. supplementary movie
Video of reflective interferometry taken from below an impacting drop (𝝂 = 1,000 cSt; Rb= 1.88 mm; V = 1.09 m/s). The video was recorded at 500 kfps and is played back at 10 fps. The horizontal extent is 1.76 mm.

 Video (4.7 MB)
4.7 MB
VIDEO
Movies

Langley et al. supplementary movie
Video of reflective interferometry taken from below an impacting drop (𝝂 = 10 cSt; Rb= 1.90 mm; V = 1.20 m/s). The video was recorded at 500 kfps and is played back at 10 fps. The horizontal extent is 0.82 mm.

 Video (1.1 MB)
1.1 MB
VIDEO
Movies

Langley et al. supplementary movie
Video of reflective interferometry taken from below an impacting drop (𝝂 = 100 kcSt; Rb= 1.50 mm; V = 2.96 m/s). The video was recorded at 500 kfps and is played back at 10 fps. The horizontal extent is 1.76 mm.

 Video (3.1 MB)
3.1 MB
VIDEO
Movies

Langley et al. supplementary movie
Video of reflective interferometry taken from below an impacting drop (𝝂 = 1,000 cSt; Rb= 1.88 mm; V = 1.09 m/s). The video was recorded at 500 kfps and is played back at 10 fps. The horizontal extent is 1.76 mm.

 Video (4.3 MB)
4.3 MB
VIDEO
Movies

Langley et al. supplementary movie
Video of reflective interferometry taken from below an impacting drop (𝝂 = 100 kcSt; Rb= 1.50 mm; V = 2.96 m/s). The video was recorded at 500 kfps and is played back at 10 fps. The horizontal extent is 1.76 mm.

 Video (3.6 MB)
3.6 MB
VIDEO
Movies

Langley et al. supplementary movie
Video of reflective interferometry taken from below an impacting drop (𝝂 = 10 cSt; Rb= 1.90 mm; V = 1.20 m/s). The video was recorded at 500 kfps and is played back at 10 fps. The horizontal extent is 0.82 mm.

 Video (785 KB)
785 KB
VIDEO
Movies

Langley et al. supplementary movie
Video of reflective interferometry taken from below an impacting drop (𝝂 = 1 McSt; Rb= 1.55 mm; V = 2.10 m/s). The video was recorded at 100 kfps and is played back at 10 fps. The horizontal extent is 1.38 mm.

 Video (4.1 MB)
4.1 MB
VIDEO
Movies

Langley et al. supplementary movie
Video of reflective interferometry taken from below an impacting drop (𝝂 = 1 McSt; Rb= 1.55 mm; V = 2.10 m/s). The video was recorded at 100 kfps and is played back at 10 fps. The horizontal extent is 1.38 mm.

 Video (5.2 MB)
5.2 MB

Metrics

Full text views

Total number of HTML views: 8
Total number of PDF views: 239 *
Loading metrics...

Abstract views

Total abstract views: 576 *
Loading metrics...

* Views captured on Cambridge Core between 23rd January 2017 - 20th November 2017. This data will be updated every 24 hours.