MODELING OF SALTATION AND TURBULENCE EFFECTS IN A HORIZONTAL GAS-SOLID BOUNDARY-LAYER

This work is devoted to the study of the behavior of solid particles i n a horizontal air boundary layer. A two-fluid model is selected to an alyze the particle motion in the mixed regime where both saltation and turbulence effects are important. Boundary layer approximations are a pplied to the solid phase equations, using conventional space/time ave raging. Resulting equations are shown to be in agreement with the phas e avenged equations generally used in two-fluid models. Closure is ach ieved by means of a gradient law, however the particle diffusion and m omentum transfer coefficients are distinguished using a variable parti cle Schmidt number. Turbulent particle diffusion is modeled using an a vailable analytical model, which is modified to take the saltation eff ect into account in the particle r.m.s. velocity. Comparison between e xperimental and numerical results shows that the following analysis is acceptable within the experimental and numerical error. The model sli ghtly underestimates the particle mean velocity in the outer region of the boundary layer, but yields satisfactory values of mass fluxes. Th e present simple approach adequately describes the particle behavior i n a horizontal turbulent boundary layer, with the main originality bei ng the realistic dependence of the particle Schmidt number upon the sa ltation phenomenon.