Voidage particle-fluid system

Fp/fi. Assuming, after Mertes and Rhodes (1955) and Lapidus and Elgin (1957), that for monodisperse fluid-particle systems, the relative or slip velocity is a unique function of voidage (or vice versa) irrespective of the flow direction of either fluid or particles, it follows that U = — Fp. Thus plots of Fp vs. have frequently been interpreted as equivalent to those of 7 vs. . Some caution should be exercised in assuming this... 

Foscolo, P.U., Gibilaro, L.G. and Rapagna, S. (1995). Infinitesimal and finite voidage perturbations in the compressible particle-phase description of a fluidized bed. In Developments in Fluidization and Fluid-Particle Systems (J.C. Chem, ed.). AIChE Symposium Series, 91(308), 44. 

Di Felice, R., 1994. The voidage function for fluid-particle interaction systems. International Journal of Multiphase Flow, 20, 153-159. 

Difelice, R. The voidage functimi for fluid-particle interactimi systems. Int. J. Multiph. Flow 20, 153-159, 1994. 

Kwauk (1963) predicted a state of flooding, in which state the voidage of the fluidized bed increase suddenly, and as a result, the particles in the fluidized dipleg overflow from the top of the dipleg. According to the definition of flooding, it occurs in a particle-fluid system at the following condition ... 

By applpng a force balance, calculate the incipient fluidizing velocity for a system with particles of particle density 5000 kg/m and mean volume diameter 100 xm and a fluid of density 1.2kg/m and viscosity 1.8x10 Pas. Assume that the voidage at incipient fluidization is 0.5. 

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