Transport of inertial particles in compressible turbulent boundary layers with thermal effects

The Eulerian–Lagrangian approach is employed to simulate a compressible turbulent boundary layer laden with inertial particles at Mach numbers 0. 95, 2, 6 and 7. The governing equations for the five-species reacting compressible fluid are solved using the direct numerical simulations method. The particle motion equations involve thermophoretic force besides the drag force because thermal effects become significant. Results show that the thermal effects significantly alter the near-wall particle accumulation. Specifically, a distinct peak in particle concentration emerges at y^+ 3, which is absent when thermal effects are neglected and particle wall-normal transport is controlled by turbophoresis. This phenomenon is attributed to the alternating positive and negative structures in the near-wall region. In the outer layer, particles tend to accumulate on the turbulent side of the turbulent/non-turbulent interface (TNTI) due to the centrifugal effect of large-scale vortices and the combined barrier effect of potential flow. Meanwhile, particles also accumulate in the lower downstream region of the bubbles generated by the engulfment of the TNTI. As the Mach number increases, the near-wall particle concentration peak becomes clear, but the particle accumulation near the TNTI becomes less pronounced. On the horizontal plane, particles tend to distribute in the low-speed streaks near the wall, while accumulating at the inward cusps near the TNTI. The tendency for near-wall preferential distribution is weakened by the particle up/down transport induced by the alternating positive and negative structures. However, the distribution area seen by the TNTI becomes larger because the TNTI is less wrinkled as the Mach number increases.