On the role of grazing atmospheric particles in hypersonic boundary-layer receptivity

Sean Dungan; Christoph Brehm

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arXiv · 2611.05639

On the role of grazing atmospheric particles in hypersonic boundary-layer receptivity

Sean Dungan·Christoph Brehm

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Abstract

The role of small atmospheric particulates in the initiation of the laminar-turbulent transition is investigated for the HIFLIER vehicle during Mach 6 ascent condition. High-fidelity simulations are used to examine the disturbance wavepackets generated by particles following either grazing trajectories through the boundary layer or trajectories that lead to impact and rebound at the cone surface. Grazing particles that penetrate less than halfway through the boundary layer are found to generate wavepackets with amplitudes comparable to those produced by wall-impinging particles. To identify the receptivity mechanisms responsible for this behaviour, a multiple-scales asymptotic formulation is developed that accounts for the extended streamwise region over which a particle interacts with the boundary layer. The analysis shows that a grazing particle can generate a strong disturbance response when crossing the critical layer, where the streamwise-momentum component of the adjoint mode is largest and the boundary layer is most receptive. Thus, direct surface impact is not required for atmospheric particulates to excite dynamically significant instability waves. Root-mean-square disturbance estimates for submicron grazing particles predict transition-onset locations close to those measured in flight, suggesting they may have contributed significantly to the onset of transition on HIFLIER at the trajectory condition considered.

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Sean Dungan, Christoph Brehm. 2026-11-03. On the role of grazing atmospheric particles in hypersonic boundary-layer receptivity. https://arxiv.org/abs/2611.05639

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