Definition of the Single Drop Breakup Event

Abstract

Experiments are performed to record data of single drop breakup events in turbulent flow (stirred tank conditions) for improved understanding of the breakup phenomena. Different interpretations can be made of a multiple breakup event, in particular, either the initial breakup can be evaluated, or the entire breakup cascade can be considered. The examining of these two breakup definitions in the present study reveals that the binary breakup event, which is the most frequent used assumption for the number of daughter drops in the literature, is only a rough assessment of the physical truth. For a 1 mm toluene drop up to 47 daughter drops as a consequence of an entire breakup sequence were counted and the arithmetic average value was 11.7 with standard deviation of 7.7. The corresponding average value for the initial breakup was 2.39. By high-speed imaging it is possible to break down the breakup cascade into binary breakups. However, the isolation of these individual breakups is a strong simplification of the breakup process. The breakups in the cascade are triggered by the initial breakup and are not statistically independent. It is more meaningful to evaluate not only the initiation of a drop breakup but the whole sequence of the breakup cascade. The breakup time of the two breakup definitions appears significantly different. For a 1 mm toluene drop the difference in the arithmetic breakup time was 129 ms. The relative number distribution of the breakup time is wider for the breakup cascade than for the initial breakup as it is influence by the wider range and higher number of daughter drops. Resolution limitations of the camera used did not allow determination of the complete daughter size distribution of the final drop population of the breakup cascade with sufficient accuracy. Two different experimental set-ups were used to verify the general trends of the breakup definitions.

Two-Phase Bubble Columns: A Comprehensive Review

“…Some examples of daughter bubble size distributions are (i) statistical distribution (i.e., normal or the uniform); (ii) empirical distribution; or (iii) phenomenological distribution [214]. In this regard, the reader may refer to the experimental high-speed imaging of Solsvik et al [502]: they conducted in an attempt to understand the break-up cascade; in particular, they found that the assumption of binary breakup in the PBM approach is acceptable only if the initial breakup is analyzed.…”

Direct measurement of droplet breakage in a pulsed disc and doughnut column

“…Much effort has been done on this issue in the past century and numbers of works could be found in literature. [18][19][20][21][22][23][24][25][26][27][28] We will focus on the droplet breakage in this work.…”

Droplet breakage and coalescence in liquid–liquid dispersions: Comparison of different kernels with EQMOM and QMOM

“…[24][25][26][27] Purely kinematic break-up model was proposed by Martinez-Bazan et al 28 Another problem relates to the number of daughter drops. Solsvik et al 29,30 used high-speed imaging experiments to study the influence of mother drop size on the number of produced fragments. Comparing their results to earlier similar studies, 31,32 they observed that multiple breakage is more likely for large droplets.…”