Photographic Investigation of the Projection of Droplets by Bubbles Bursting at a Water Surface

Abstract

Bubbles of air reaching the air‐water interface burst and eject liquid droplets into the air to heights large compared to their diameter. Photographic evidence is introduced to prove the existence of a jet of liquid which upon breaking up produces these droplets. The jet is shown to be produced by the collapse of the bubble cavity. The droplets are found to be of the order of one tenth of the bubble size, for the range investigated (0.2 to 1.8 mm diameter), each bubble producing about 5 droplets. The droplet‐producing mechanism is essentially the same for fresh and sea water or sea water with oleic acid surface film. The time required for the bubble to burst and the jet formation to take place is found to be proportional to the bubble size. The sea water droplets produced by this mechanism leave, upon evaporation of the water, salt nuclei having the size range observed by Woodcock (1952). It is suggested that such bursting of bubbles plays an important role in the natural production of air‐borne sea‐salt nuclei at the sea surface.

Concentration and removal of liquid microlayers from a seawater surface by bursting bubbles1

“…The bubble, when it reaches the surface, bursts through the monomolecular layer and forms a central jet which creates the drops that are to bc collected. The rupture of the bubble film cap and monolayer OCCLII'S in less than 30 pusec (Kientzler et al 1954), while the formation of the central jet requires about 1,000 psec ( MacIntyre 1972). Since these two events are widely separated in time, the situation immediately following the rupture of the film cap may be viewed as one in which the film cap is rapidly contracting while the surface of the liquid is indented by the hemisphcroidal cavity that remains after the bubble h'as burst.…”

Seven problems in bubble and jet drop researches 1

“…In the seawater case high-speed motion pictures (Kientzler et al 1954) show that the bubble, upon reaching the surface, overshoots and rises perhaps half its diameter through the surface before surface tension forces pull it back down to an equilibrium position. In this position the bubble is stationary and mostly below the surface.…”

The sizes of the jet drops produced by air bubbles bursting on sea- and fresh-water surfaces

“…The mechanics of bubble bursting has been widely studied (Afeti and Resch, 1990;Blanchard, 1958Blanchard, , 1963Blanchard, , 1989Blanchard, , 1990Syzdek, 1975, 1988;Coantic, 1980;Coantic et al, 1981;Day, 1964;Dekker and De Leeuw, 1993;Detwiler and Blanchard, 1978;Kientzler et al, 1954;Macintyre, 1972;Resch et al, 1986;Afeti, 1991, 1992;Spiel, 1992;Toba, 1959;Woodcock et al, 1953). In order to understand and to model this air-sea interTellus 46B (1994 ), 4 action it is vital to determine the details of the bursting of single bubbles.…”

“…The upward jet is unstable and usually breaks up into a number of droplets called jet drops. Kientzler et al ( 1954) used high speed cameras to show the rising jet and its breakup.…”