Results and discussion
The examples of MBs analysis are
shown in Figure. 3, the difference in diameter of bubbles in the focal
length range can be seen, and bubbles range in diameter from about 10
μm to 200 μm. Throughout the
whole process of analysis of the video, the shape of the bubbles is
regular. It is clear that the majority of the bubbles were spherical
owing to the surface tension. To understand the effect of different test
times on the number of bubbles, we studied the bubbles captured in each
set of 1600 images. Figure 4 shows a large difference in the density of
bubbles in every experiment. Comparing the average density of bubbles
calculated for each group of 10 experiments, the maximum difference in
the number density of captured bubbles is about
150,000/cm3, indicating that the manual reciprocating
motions greatly impact the number of bubbles produced.
Figure 5 displays the statistical
histograms of the BSD in two example operations, showing that the bubble
size distribution is very close to the log-normal distribution, which is
a feasible model used to describe the microbubble size distribution in
the experiment. The expression for log-normal distribution is shown as
follows (24) :