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Hydrodynamic effects of particle chaining in liquid-solid magnetofluidized beds : theory, experiment, and simulation

In a fluidized bed of magnetically susceptible particles, the presence of
a magnetic field induce the formation of particle chains due to interparticle
magnetic forces. The resulting effect is a change in the overall spatial
distribution of the particles, transitioning from a random, isotropic distribution
to an ordered, anisotropic distribution. For a magnetic field with the same
direction as the superficial fluid velocity, the resulting structures offer less
resistance to flow, resulting in a decrease of the effective drag coefficient.
Thus the bed is less expanded and have lower voidage in the presence of the
magnetic field, at a given fluid superficial velocity.
The effect of particle chaining in the particle drag in a liquid-solid
fluidized bed is studied. Experimental data is collected on voidage and
pressure drop for particle Reynolds number between 75 and 190, and for
particle chain separation force to buoyant weight ratio between 0 and 0.58.
A two-parameter equation for the change in drag coefficient with
respect to the hydrodynamic and magnetic operating conditions in the bed is
obtained. It provides very good agreement with the experimental data.
A proprietary 3-D simulation code implementing a Computational Fluid
Dynamics-Discrete Particle Method is developed and tested under the same
conditions as the experiments performed. Without the use of any correction in
the drag coefficient, the simulation code overestimates the bed expansion by
as much as 70%. This error is reduced to or below 10% when the drag
coefficient is corrected using the equation here obtained. / Graduation date: 2005
Date27 April 2005
CreatorsCruz-Fierro, Carlos Francisco
ContributorsJovanovic, Goran N.
Source SetsOregon State University
Detected LanguageEnglish

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