Papers Published
Abstract:
The pinch-off of a drop of viscous fluid is observed using
high-speed digital imaging. The behavior seen by previous
authors is observed here; namely, the filament that attaches
the drop to the orifice evolves into a primary thread
attached to a much thinner, secondary thread by a slight
bulge. Here, we observe that the lengths of the primary and
secondary threads are reproducible among experiments to
within 3% and 10%. The secondary thread becomes unstable as
evidenced by wave-like disturbances. The actual pinch-off
does not occur at the point of attachment between the
secondary thread and the drop. Instead, it occurs between
the disturbances on the secondary thread. After the initial
pinch-off, additional breaks occur between the disturbances,
resulting in several secondary satellite drops with a broad
distribution of sizes. The pinch-off of the thread at the
orifice is similar to that at the drop with one main
difference: there is no distinct secondary thread. Instead,
the primary thread necks down monotonically until wave-like
disturbances form, resulting in pinch-off at multiple sites
in between. The speed of the tips of the retreating,
secondary threads after pinch-off are reported and discussed
in the context of various scaling laws.