Voidage Functions

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

Note that for a normal packed bed, e = 0.4, the voidage function assumes a value in excess of 30 in the limit, as e —> 1, it approaches zero. By simply adding 1 to the general voidage function expression, the correct, unhindered limit is approached without significantly affecting... 

Figure 3.3 Voidage functions for drag on a particle in a particle bed Continuous curve, the common adopted form, open squares, the viscous regime form, 3.33(1 e)/e + 1 solid squares, the inertial regime form, 3.55...

We are therefore led to adopt the more compact form for the voidage function, leading to the following relations for the drag force on a particle in a particle bed ... 

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