Extension of Hill-Koch-Ladd drag correlation over all ranges of Reynolds number and solids volume fraction

Hill et al. [R. J. Hill, D.L. Koch, J.C. Ladd, J. Fluid Mech. (2001), 448, pp. 213-241 and 243-278] proposed a set of drag correlations, based on data from Lattice-Boltzmann simulations. These correlations, while very accurate within the range of void fractions and Reynolds numbers used in the Lattice-Boltzmann simulations, do not cover the full range of void fractions and Reynolds numbers encountered in fluidized bed simulations. In this paper a drag correlation applicable to the full range of void fractions and Reynolds numbers is developed by blending the Hill-Koch-Ladd (HKL) drag correlation with known limiting forms of the gas-solids drag function such that the blended function is continuous with respect to Reynolds number and void fraction. This study also corrects a misinterpretation of the HKL drag correlation that was published in the literature, which makes the drag function discontinuous with respect to the Reynolds number. Two examples of gas/solids flows in a bubbling fluidized bed and a one-dimensional channel flow are used to illustrate differences between the proposed extension of HKL drag correlation and another form published in the literature. (c) 2005 Elsevier B.V. All rights reserved.