Mixed Convection in a Particle-Laden Channel Flow: One and Two-Way Coupling Regimes

In the present work, by means of Eulerian-Lagrangian DNSs within the point-particle approach, we have studied the modulation of the fluid and particle temperature fields in the channel flow operated by the momentum and energy transfer between the two phases, when also buoyancy forces acting on the fluid are taken into account. We performed simulations at a single friction Reynolds number, Re_tau=180, and Prandtl number, Pr=0.71, while we varied the Richardson number from 0.272 to 27.2, and the Stokes number between 0.6 and 120. Both the one and the two-way coupling regimes were explored in order to evaluate the influence of particles on the fluid. When buoyancy effects are weak, particle feedback significantly influences fluid statistics, whereas its impact seems to diminish and become negligible as natural convection becomes dominant. Particle statistics are showcased across various Stokes numbers, emphasizing how buoyancy-induced enhancement of vertical motions reduces particle concentration near the wall.