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Space-time
diagrams of inertio-elastic Couette flow
Space time diagrams of Couette flow of a polymer solution in the
regime of weak (a-b) to moderate (c) elasticity (Groisman and Steinberg,
PRL 96). The primary instability is driven by inertial forces, but
flow patterns above the instability threshold are modified by elastic
effects. The flow was visualized with light reflecting Kalliroscope
flakes under ambient illumination. Brightness profiles along a line
parallel to the axis of the Couette-Taylor column were taken in
consecutive moments of time (12.5 times per second) and plotted
from top to the bottom...
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Patterns
in elastic Couette flow
Snapshots of different patterns appearing
in the Couette-Taylor flow in a highly elastic polymer solution
(Groisman and Steinberg, PRL 97). The flow was visualized with light
 reflecting
Kalliroscope flakes and laser sheet illumination. A laser beam expanded
to a thin sheet of light...
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Solitary
vortex pairs, diwhirls
A snapshot of Taylor column with solitary
vortex pairs, diwhirls (Groisman and Steinberg, PRL 97) The flow
was visualized by light reflecting Kalliroscope flakes in ambient
light. The stationary outer...
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Coalescence
of diwhirls
If the distance between two solitary vortex
pairs, diwhirls, is sufficiently small (less than about five times
the size of the gap in the Taylor column), they slowly drift towards
each other and finally coalesce...
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Elastic
turbulence with Kalliroscope flakes
Snapshots of the elastic turbulence in a flow between two plates,
(Groisman and Steinberg, Nature 2000). The Weissenberg number was
6.5 for the upper row and 13 for the lower row. The Reynolds number
was below unity. The rotating upper plate was black. Its radius
was 38 mm and the gap between the plates was 10 mm. The working
liquid, an elastic polymer solution, was seeded with light reflecting
Kalliroscope...
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Elastic
turbulence with ink
Elastic turbulence visualized with ink. Snapshots of mixing in
the flow between two plates were made in consecutive moments of
time. The rotating upper plate was white. The flow was illuminated
and photographed through the transparent stationary lower plate...
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Mixing
in a channel
A schematic drawing of a curvilinear channel used in the mixing
experiment (above) and snapshots of mixing at different stages
(Groisman and Steinberg, Nature 2001). The channel is d = 3 mm
deep, machined in a transparent bar of Plexiglas and sealed from
above by a transparent window. It consists of a sequence of smoothly
connected half-rings with the inner and outer radii R1 = 3 mm
and R2 = 6 mm, respectively. Two liquids are fed into the channel
by two syringe pumps at equal discharge rates...
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Space-time
diagrams of mixing in the channel
Space-time plots illustrating mixing of polymer solutions in the
curvilinear channel (see above) at different distances from the
inlet (the distances are proportional to the number N). Efficient
mixing is due to a random similar to the elastic turbulence. Brightness
profile was captured 12.5 times per second along a single line
across the channel near the middle of a half-ring (a horizontal
line in the middle in the images above). Profiles taken in consecutive
moments of time are plotted as horizontal lines from top to the
bottom. The space...
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Microfluidic
rectifier
Photographs of microfluidic rectifier and close-ups of its different
parts. Fluidic rectifier is channel of a special shape, which
acts as a diode. At the same applied pressure, flux of fluid through
the channel is different for flows in opposite directions. A macroscopic
fluidic rectifier was...
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