Drag coefficient Ergun

The dimensionless drag coefficient fiL/ ps u0) in Eq. (30) can be expressed in terms of other fluid parameters by the use of Eqs. (31-33). For low voidages where the Ergun-like expression holds,... 

Since the same simplified set of dimensionless parameters holds exactly at both high and low Reynolds numbers, it is reasonable to expect that it will hold, at least approximately, over the entire range of conditions for which the drag coefficient can be determined by the Ergun equation or an equation of similar form. 

Ergun, S. 1952 Fluid flow through packed columns. Chtan. Eng. Prog. 48(2), 89-94, 1952. Gibilaro, L. G., Felice, R. I. D., and Waldram, S. P. Generalized ftiction factor and drag coefficient correlations for fluid-particle interactitms. Chem. Eng. Sci. 40, 1817-1823, 1985. 

The interphase momentum transfer coefficient P is frequently modeled by a combination of the Ergun equation and the Wen and Yu correlation, but in this model, the improved drag relation by Beetstra et al. (2007), based... 

In the drag force, the influence of the gas on the particle is described with interphase momentum transfer coefficient P p which is calculated depending on the porosity of the soHd phase e. For the dense regimes, when porosity is smaller than 0.8, the coefficient is calculated according to the Ergun correlation (Ergun, 1952) ... 

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