Evaluation of boundary conditions used to model dilute, turbulent gas/solids flows in a pipe

The turbulent gas/solids flow model based on the work of Simonin [1] [Simonin, O., 1996. Continuum modeling of dispersed two-phase flows, in Combustion and Turbulence in Two-Phase Flows, Von Karman Institute of Fluid Dynamics Lecture Series 1996-2] is able to predict reasonably well dilute gas/solids flows with appropriate boundary conditions (BC). Four different types of boundary conditions were investigated to assess their sensitivity. The experimental data fall between the large-friction/no-sliding and small-friction/all-sliding limits of Jenkins and Louge [4] [J.T. Jenkins, M.Y. Louge, On the flux of fluctuating energy in a collisional grain flow at a flat frictional wall, Phys. Fluids 9 (10), (1997) 2835-2840] BC. However, the physical behavior of the particle-wall interactions is close to the small-friction/all-sliding limit of Jenkins and Louge BC or the Johnson and Jackson [5] [P.C. Johnson, R. Jackson, Frictional-collisional constitutive relations for granular materials, with application to plane shearing. J. Fluid Mech. 176 (1987) 67-93]BC with a small specularity coefficient or simply the free-slip BC.