892 research outputs found
Viscous to Inertial Crossover in Liquid Drop Coalescence
Using an electrical method and high-speed imaging we probe drop coalescence
down to 10 ns after the drops touch. By varying the liquid viscosity over two
decades, we conclude that at sufficiently low approach velocity where
deformation is not present, the drops coalesce with an unexpectedly late
crossover time between a regime dominated by viscous and one dominated by
inertial effects. We argue that the late crossover, not accounted for in the
theory, can be explained by an appropriate choice of length-scales present in
the flow geometry.Comment: 4 pages, 4 figure
3D tracking of particles in a dusty plasma by laser sheet tomography
The collective behavior of levitated particles in a weakly-ionized plasma
(dusty plasma) has raised significant scientific interest. This is due to the
complex array of forces acting on the particles, and their potential to act as
in-situ diagnostics of the plasma environment. Ideally, the three-dimensional
(3D) motion of many particles should be tracked for long periods of time.
Typically, stereoscopic imaging using multiple cameras combined with particle
image velocimetry (PIV) is used to obtain a velocity field of many particles,
yet this method is limited by its sample volume and short time scales. Here we
demonstrate a different, high-speed tomographic imaging method capable of
tracking individual particles. We use a scanning laser sheet coupled to a
single high-speed camera. We are able to identify and track tens of individual
particles over centimeter length scales for several minutes, corresponding to
more than 10,000 frames.Comment: 7 pages, 5 figure
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