On the influence of near-wall forces in particle-laden channel flows

摘要

Computation of a turbulent dilute gas-solid channel flow has been undertaken to study the influence of using wall-corrected drag coefficients and of the lift force on the dispersed phase characteristics. The incompressible Navier-Stokes equations governing the carrier flow were solved by using a direct numerical simulation approach and coupled with a Lagrangian particle tracking. Calculations were performed at Reynolds number based on the wall-shear velocity and channel half-width, Re-tau approximate to 184, and for three different sets of solid particles. For each particle set, two cases were examined, in the first one the particle motion was governed by both drag and lift wall-corrected forces, whereas in the other one, the standard drag force (not corrected) was solely acting. The lift force model used represents the most accurate available expression since it accounts for weak and strong shear as well as for wall effects. For this study, we considered elastic collisions for particles contacting the walls and that no external forces were acting. Present results indicate that the use of the lift force and of the drag corrections does not lead to significant changes in the statistical properties of the solid phase, at the exception of some statistics for the high inertia particles. (c) 2006 Elsevier Ltd. All rights reserved.