Effects of solid inertial particles on the velocity and temperature statistics of wall bounded turbulent flow

The effect of solid inertial particles on the velocity and temperature statistics of a non-isothermal turbulent channel flow is studied using direct numerical simulation. The particles inertia is varied by changing the particles diameter. The density of particles is kept constant. A two-way coupled Eulerian-Lagrangian approach is adopted to solve the carrier flow field and the motion of dispersed particles. Three different particle Stokes numbers of St = 24, 60, 192, at a constant particle mass loading of phi(m) = 0.54, are considered. The mean and rms profiles of velocity and temperature for fluid and particles, and the scatter plots of fluid-particle temperature differences are presented. In addition, the variations of different budget terms for the turbulent kinetic energy equation and fluctuating temperature variance equation in the presence of particles are reported. The fluid turbulent heat flux is reduced by the presence of particles, and in spite of the additional heat exchange between the carrier fluid and the particles, the total heat transfer rate stays always lower for particle-laden flows. To further clarify this issue, the total Nusselt number is split into a turbulence contribution and a particle contribution, and the effects of particles inertia on fluid turbulent heat flux and fluid-particle heat transfer are examined in detail. (C) 2016 Elsevier Ltd. All rights reserved.