Marangoni flotation of liquid droplets

R. Savino, D. Paterna, M. Lappa

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Flotation of liquid droplets on pool surfaces, in the presence of temperature differences, is studied experimentally and numerically. Coalescence or sinking of the droplet is prevented by the thermal Marangoni motion, owing to the surface tension imbalance at the pool surface. The mechanism is the same as that investigated in previous works on coalescence and wetting prevention in the presence of temperature differences. If the droplet is colder than the liquid surface, the flow is directed radially towards the drop; this radial flow field drags the ambient air under the drop, thus creating an air film and avoiding a direct contact between the droplet and the pool molecules. The surface velocities are measured visually with a CCD camera to image the motion of tracers floating on the pool surface; the surface temperature distributions along the pool and the droplet surfaces are measured by an infrared thermocamera. The experimental results are correlated by numerical results obtained under the assumption of spherical drop and axisymmetric flow regime. Different liquids are considered and the influence of evaporation is discussed, showing a good agreement between the experiments and the numerical simulations.
LanguageEnglish
Pages307-326
Number of pages20
JournalJournal of Fluid Mechanics
Volume479
DOIs
Publication statusPublished - 2003

Fingerprint

flotation
Flotation
Liquids
liquids
coalescing
temperature gradients
axisymmetric flow
radial flow
Coalescence
sinking
liquid surfaces
air
CCD cameras
floating
surface temperature
wetting
drag
tracers
flow distribution
interfacial tension

Keywords

  • liquid droplets
  • flotation
  • thermal Marangoni motion

Cite this

Savino, R. ; Paterna, D. ; Lappa, M. / Marangoni flotation of liquid droplets. In: Journal of Fluid Mechanics. 2003 ; Vol. 479. pp. 307-326.
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Marangoni flotation of liquid droplets. / Savino, R.; Paterna, D.; Lappa, M.

In: Journal of Fluid Mechanics, Vol. 479, 2003, p. 307-326.

Research output: Contribution to journalArticle

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T1 - Marangoni flotation of liquid droplets

AU - Savino, R.

AU - Paterna, D.

AU - Lappa, M.

PY - 2003

Y1 - 2003

N2 - Flotation of liquid droplets on pool surfaces, in the presence of temperature differences, is studied experimentally and numerically. Coalescence or sinking of the droplet is prevented by the thermal Marangoni motion, owing to the surface tension imbalance at the pool surface. The mechanism is the same as that investigated in previous works on coalescence and wetting prevention in the presence of temperature differences. If the droplet is colder than the liquid surface, the flow is directed radially towards the drop; this radial flow field drags the ambient air under the drop, thus creating an air film and avoiding a direct contact between the droplet and the pool molecules. The surface velocities are measured visually with a CCD camera to image the motion of tracers floating on the pool surface; the surface temperature distributions along the pool and the droplet surfaces are measured by an infrared thermocamera. The experimental results are correlated by numerical results obtained under the assumption of spherical drop and axisymmetric flow regime. Different liquids are considered and the influence of evaporation is discussed, showing a good agreement between the experiments and the numerical simulations.

AB - Flotation of liquid droplets on pool surfaces, in the presence of temperature differences, is studied experimentally and numerically. Coalescence or sinking of the droplet is prevented by the thermal Marangoni motion, owing to the surface tension imbalance at the pool surface. The mechanism is the same as that investigated in previous works on coalescence and wetting prevention in the presence of temperature differences. If the droplet is colder than the liquid surface, the flow is directed radially towards the drop; this radial flow field drags the ambient air under the drop, thus creating an air film and avoiding a direct contact between the droplet and the pool molecules. The surface velocities are measured visually with a CCD camera to image the motion of tracers floating on the pool surface; the surface temperature distributions along the pool and the droplet surfaces are measured by an infrared thermocamera. The experimental results are correlated by numerical results obtained under the assumption of spherical drop and axisymmetric flow regime. Different liquids are considered and the influence of evaporation is discussed, showing a good agreement between the experiments and the numerical simulations.

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KW - thermal Marangoni motion

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JF - Journal of Fluid Mechanics

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