Figure Captions
FIGURE
1 Schematic of the experimental apparatus.
FIGURE 2 Bubble growth, departure and coalescence from a
downward-pointing nozzle captured under illumination by a mental-halide
light.
FIGURE 3 (a) Close-up of bubble coalescence recorded by a LED
light (R 0=0.085 mm, Q =1299 ml/min), (b)
Detailed process of surface-wave travel and pinch-off recorded in a
mental-halide light (R 0=0.085 mm, Q =1400
ml/min), (c) Another side-view of pinch-off and liquid jet recorded in a
LED light (R 0=0.085 mm, Q =1191 ml/min).
FIGURE 4 Superimposed profiles spanning the travel of capillary
waves and pinch-off shown in Figure 3(b).
FIGURE 5 Typical bubble behaviors from an upward-pointing
nozzle recorded under illumination by a LED light
(R 0=0.085 mm, Q =54.4 ml/h).
FIGURE 6 . An illustration of the formation process of
microbubbles.
FIGURE 7 Normalized pinch-off time by the capillary time versus
Ohnesorge number of mother bubble.
FIGURE 8 Phase diagram for partial coalescence depending on
Ohnesorge number of mother bubble and relative size of parent bubbles.
FIGURE 9 Phase diagram for no bubble coalescence (I),
coalescence without pinch-off (II), coalescence with generation of
microbubbles (III), and irregular coalescence (IV) depending on Weber
and Bond numbers.
FIGURE 10 Variation in microbubble size for different values of
Weber and Bond numbers.
FIGURE
11 Distribution of normalized microbubble diameter by its average
value.
FIGURE 12 (a) Comparison of Eq. (10) with experimental
data. The solid line fits the
experimental data following the trend
(Ds /Lb )/Bo9/20∝We1/4.
The error bar on the exponent is 3/40 and two bounds are plotted with
dotted lines, (b) Ratio of satellite surface energy to the kinetic
energy of the gas flow. The solid line fits the experimental data
following the trendEs /Ek ∝We-5/3.