Marangoni flotation of liquid droplets

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 s...

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Bibliographic Details
Published in:Journal of fluid mechanics 2003-03, Vol.479, p.307-326, Article S0022112002003610
Main Authors: SAVINO, R., PATERNA, D., LAPPA, M.
Format: Article
Language:English
Subjects:
Drops and bubbles
Exact sciences and technology
Flow velocity
Fluid dynamics
Fluid mechanics
Fundamental areas of phenomenology (including applications)
Nonhomogeneous flows
Numerical analysis
Physics
Surface tension
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Summary: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.
ISSN:0022-1120
1469-7645
DOI:10.1017/S0022112002003610