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Forces on a boiling bubble in a developing boundary layer, in microgravity with g-jitter and in terrestrial conditions

Van der Geld, Cees and Colin, Catherine and Segers, Quint and Pereira da Rosa, V.H. and Yoshikawa, Harunori Forces on a boiling bubble in a developing boundary layer, in microgravity with g-jitter and in terrestrial conditions. (2012) Physics of Fluids, 24 (8). ISSN 1070-6631

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Official URL: http://dx.doi.org/10.1063/1.4743026

Abstract

Terrestrial and microgravity flow boiling experiments were carried out with the same test rig, comprising a locally heated artificial cavity in the center of a channel near the frontal edge of an intrusive glass bubble generator. Bubble shapes were in microgravity generally not far from those of truncated spheres,which permitted the computation of inertial lift and drag from potential flow theory for truncated spheres approximating the actual shape. For these bubbles, inertial lift is counteracted by drag and both forces are of the same order of magnitude as g-jitter. A generalization of the Laplace equation is found which applies to a deforming bubble attached to a plane wall and yields the pressure difference between the hydrostatic pressures in the bubble and at the wall, p. A fully independent way to determine the overpressure p is given by a second Euler-Lagrange equation. Relative differences have been found to be about 5% for both terrestrial and microgravity bubbles. A way is found to determine the sum of the two counteracting major force contributions on a bubble in the direction normal to the wall from a single directly measurable quantity. Good agreement with expectation values for terrestrial bubbles was obtained with the difference in radii of curvature averaged over the liquid-vapor interface, (1/R2 − 1/R1), multiplied with the surface tension coefficient, σ. The new analysis methods of force components presented also permit the accounting for a surface tension gradient along the liquid-vapor interface. No such gradients were found for the present measurements.

Item Type:Article
HAL Id:hal-00873953
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Eindhoven University of Technology - TU/e (NETHERLANDS)
Laboratory name:
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Deposited By: Catherine COLIN
Deposited On:16 Oct 2013 15:14

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