Bag breakup regimes

Chou, W.-H., L.-P. Hsiang, and G. M. Faeth. 1997. Dynamics of drop deformation and formation during secondary breakup in the bag breakup regime. AIAA Paper No. 97-0797. 

W. H. Chou, G. M. Faeth Temporal Properties of Secondary Drop Breakup in the Bag Breakup Regime, Inti. J. Multi. Flow 24(6), 889-912 (1998). 

In the breakup regimes, a droplet may undergo secondary breakup when the breakup time is reached. The droplet size distribution after bag or multimode breakup may follow the Simmons root-normal distribution pattern 264 with MMD/SMD equal to 1.1,... 

The breakup parameter, Kbu, in the bag breakup and the stripping breakup regime is proportional to the characteristic breakup frequencies suggested by [5]. The characteristic breakup frequency for the catastrophic breakup regime is derived from the study of the RT instability by Bellman and Pennington [21] as reported by Patterson and Reitz [11]. The constant k = 0.05 has been determined such that the drop radii match the phase Doppler measurements of Schneider [22], whereas the values for the constants ki and k are chosen such that Kbu is continuous at the regime-dividing Weber numbers, Web,s and Wcg c-... 

The fine fraction of the droplet fragments is distributed as in bag and multimode breakup regimes based on a reduced SMD which is derived from the Sauter mean diameter dj,z given by (18.15) and the maximum stable diameter by (18.16), as... 

Other breakup structures have also been observed to occur in the multimode regime. One example is the plume/sheet-thinning morphology identified in [16], Nevertheless, all of these structures can be thought of as resembling some combination of bag- and sheet-thinning breakup. 

Non-Newtonian liquids also exhibit a transitional multimode regime between bag and sheet-thinning breakup. It is important to note that only bag/plume-type breakup has been observed. Other breakup structures discussed in the Newtonian section have not been observed for non-Newtonian drops. It is unclear if this is due to a lack of available data or some rheological difference. 

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