THE DETECTION AND DIMENSION OF BUBBLE ENTRAINMENT AND COMMINUTION

Data on bubble entrainment and comminution are gathered in three exper iments, involving the breakup of a disk of air trapped between two pla tes, and bubble cloud generation under a waterfall, and a plunging jet . In the second two cases, an automated acoustic system for characteri zing the entrainment is employed. The data sets are compared with an e xisting theory for bubble fragmentation, in which a key parameter is t he number of spatial dimensions associated with the insertion of rando mly positioned planes which are used to divide up the bubble. While an appropriate best-fit theoretical curve can be obtained for the bubble population histograms generated by air disk comminution, waterfalls a nd plunging jets produce multimodal distributions which the theory can not model. The differing roles of shape oscillations and surface waves in bubble fragmentation, and the issues involved with incorporating t hese into the model, are examined. (C) 1998 Acoustical Society of Amer ica.