Translational and rotational motions of small solid particles in a spatially developing turbulent boundary layer with heat transfer

Direct numerical simulations have been performed to investigate the translational and rotational motions of small solid particles in a spatially developing turbulent boundary layer with heat transfer and two-way coupling, using the Eulerian-Lagrangian point-particle approach. The particles are assumed to be smaller than the Kolmogorov length scale in the dilute gas-solid flow. The simulation results show that the motion of particles is affected by particle inertia, particle preferential concentration and two-way coupling. The mean particle angular velocity is slightly larger than the fluid one in the buffer layer since the small heavy particles preferentially accumulate in regions of high strain rate, whereas the particles rotate slower than the surrounding fluid in the close vicinity of the wall due to their high rotational inertia. In the streamwise direction, the fluid spin intensity exceeds the corresponding particle spin intensity, as a consequence of particle preferential concentration in regions of low streamwise fluid vorticity; while the opposite is true in the wall-normal and spanwise directions. In addition, the differences in the temperature, linear and angular velocities between different inertial particles can be explained in terms of the two-way interactions between dispersed particles and continuous fluid. (C) 2018 Elsevier Ltd. All rights reserved.