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Research in Fluid-Particle Interactions, Granular Flows, Fluidization
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Affiliated Faculty:
Lance Collins,
David Erickson,
Brian Kirby,
Michel Louge
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Multiphase flows offer a number of exciting research challenges and applications. Two-way
coupling between fluid flow and particles increases both computational and experimental complexity,
but such studies allow for fundamental understanding of particle interaction with turbulence, granular flows,
and fluidization.
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Lattice-Boltzmann simulations of a sheared flow of gas and spherical particles.
(Courtesy Rolf Verberg and Don Koch) |
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Electrodeless dielectrophoretic trapping of microparticles.
(Courtesy Brian Kirby) |
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Applications in which granular/fluidized flows (high particle loading) are crucial include powder processing,
snow and avalanche flows, while lower particle loading is important in bioanalytical and combustion
applications.
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Instrumentation for monitoring particle-laden flows can be quite
involved. Current research involves development of instruments
capable of tracking several hundred particles embedded in a
turbulent flow for long times (integral times) with high accuracy
(sub-Kolmogorov time resolution) for the purpose of analyzing particle
accelerations and multi-particle dynamics in turbulence. Cameras must
be capable of 100,000 frames per second in order to make this feasible.
In addition to the challenge with speed, the need for spatial accuracy
requires four cameras to image a single volume. Multiple cameras have been
mounted to von Karman turbulence devices and wind tunnels in MAE
and elsewhere at Cornell and image processing software is being developed
to obtain the particle trajectories from the camera images.
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Aerosol particles cluster in turbulent flows. Green surfaces are
vortex tubes where fluid circulates rapidly, centrifuging particles
out into the interstitial straining regions. White surfaces are
particle-rich regions with more than ten times the nominal particle concentration.
(Courtesy Lance Collins) |
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Microgravity experiment with a binary mixture of grains segregating under a
gradient of granular temperature. Experiments were carried out on NASA's KC-135 microgravity aircraft.
(Courtesy Michel Louge) |
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