Solid-liquid fluidized beds linearization

Ostergaard91 found that for very small sand particles, i.e., 40 through 60 and 60 through 80 mesh, the gas (nitrogen) holdup was independent of particle size and liquid (water) velocity, but increased linearly with nominal gas velocity. The gas holdup in the gas -liquid (solids-free) system was higher than that in a gas-liquid fluidized bed. 

Sergeev, Y.A. and Dobritsyn, D.A. (1995). Linear, non-linear small amplitude, steady and shock waves in magnetically stabilized liquid-solid and gas-solid fluidized beds. Int. J. Multiphase Flow, 21, 75. 

The low index of the Reynolds number indicates that values of kj change little with increases in u of as much as 200%. This reflects the unusual hydrodynamic characteristics of fluidization where particle motion within the bed is quite random and increasing u causes an increase in the circulation of particulates. Relative velocities between solid and liquid, which in fact determine hydrodynamics, do not increase linearly with u. Although Eq. (2.37) appears to correlate Nassifs results, it suffers from a basic disadvantage u occurs on both sides of Eq. (2.37) be careful that values of u do not swamp the influence of other variables. Nevertheless one can use Eq. (2.37) to get an order-of-magnitude value for /c. ... 

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