The Effects of Filament, Sheet, and Disk Breakup upon the Drop Spectrum

Abstract

The coalescence/breakup formulas introduced by Low and List included a new formulation of the coalescence efficiency and a new formulation of the fragment distribution function P, which is written as a weighted sum of three distribution functions, each corresponding to one of three types of fragmentation (filament, sheet and disk). The purpose of this work is to examine in detail the effects of each main component of the Low and List formulas upon the evolution of the drop spectrum. Compared to an earlier formulation, the Low and List coalescence efficiency tends to distribute more water mass from the small-drop range to the 1argee-drop range. The individual processes of filament and sheet breakup tend to produce single peaks in the small-drop end of the spectrum, while disk breakup tends to produce a bimodal distribution with peaks near drop diameters 1 and 2.3 mm. Disk breakup is the dominant type of fragmentation in determining the response time of the system and in causing the destruction of very large-size drops. The combined breakup processes produce a trimodal equilibrium drop distribution. Sheet breakup reinforces the small-drop peak at D = 0.23 mm established by filament breakup to form the principal mode. Sheer and disk breakup act in combination to form the less-prominent secondary and tertiary modes.