Large eddy simulation of particle-laden turbulent channel flow

Abstract

Particle transport in fully-developed turbulent channel flow has been investigated using large eddy simulation (LES) of the incompressible Navier–Stokes equations. Calculations were performed at channel flow Reynolds numbers, Reτ, of 180 and 644 (based on friction velocity and channel half width); subgrid-scale stresses were parametrized using the Lagrangian dynamic eddy viscosity model. Particle motion was governed by both drag and gravitational forces and the volume fraction of the dispersed phase was small enough such that particle collisions were negligible and properties of the carrier flow were not modified. Material properties of the particles used in the simulations were identical to those in the DNS calculations of Rouson and Eaton [Proceedings of the 7th Workshop on Two-Phase Flow Predictions (1994)] and experimental measurements of Kulick et al. [J. Fluid Mech. 277, 109 (1994)]. Statistical properties of the dispersed phase in the channel flow at Reτ=180 are in good agreement with the DNS; reasonable agreement is obtained between the LES at Reτ=644 and experimental measurements. It is shown that the LES correctly predicts the greater streamwise particle fluctuation level relative to the fluid and increasing anisotropy of velocity fluctuations in the dispersed phase with increasing values of the particle time constant. Analysis of particle fluctuation levels demonstrates the importance of production by mean gradients in the particle velocity as well as the fluid-particle velocity correlation. Preferential concentration of particles by turbulence is also investigated. Visualizations of the particle number density field near the wall and along the channel centerline are similar to those observed in DNS and the experiments of Fessler et al. [Phys. Fluids 6, 3742 (1994)]. Quantitative measures of preferential concentration are also in good agreement with Fessler et al. [Phys. Fluids 6, 3742 (1994)].