Print Email Facebook Twitter Unsteady mechanisms in shock wave and boundary layer interactions over a forward-facing step Title Unsteady mechanisms in shock wave and boundary layer interactions over a forward-facing step Author Hu, W. (TU Delft Aerodynamics; State Key Laboratory of Aerodynamics) Hickel, S. (TU Delft Aerodynamics) van Oudheusden, B.W. (TU Delft Aerodynamics) Date 2022 Abstract The flow over a forward-facing〉 step (FFS) at Ma∞ = 1.7 and Reδ0 = 1.3718 × 104 is investigated by well-resolved large-eddy simulation. To investigate effects of upstream flow structures and turbulence on the low-frequency dynamics of the shock wave/boundary layer interaction (SWBLI), two cases are considered: one with a laminar inflow and one with a turbulent inflow. The laminar inflow case shows signs of a rapid transition to turbulence upstream of the step, as inferred from the streamwise variation of 〈Cf〉 and the evolution of the coherent vortical structures. Nevertheless, the separation length is more than twice as large for the laminar inflow case, and the coalescence of compression waves into a separation shock is observed only for the fully turbulent inflow case. The dynamics at low and medium frequencies is characterized by a spectral analysis, where the lower frequency range is related to the unsteady separation region, and the intermediate one is associated with the shedding of shear layer vortices. For the turbulent inflow case, we furthermore use a three-dimensional dynamic mode decomposition to analyse the individual contributions of selected modes to the unsteadiness of the SWBLI. The separation shock and Görtler-like vortices, which are induced by the centrifugal forces in the separation region, are strongly correlated with the low-frequency unsteadiness in the current FFS case. Similarly as observed previously for the backward-facing steps, we observe a slightly higher non-dimensional frequency (based on the separation length) of the low-frequency mode than for SWBLI in flat plate and ramp configurations. Subject boundary layer separationshock wavessupersonic flow To reference this document use: http://resolver.tudelft.nl/uuid:a1ce3968-13dc-4dd7-b9f3-0a844162b6b9 DOI https://doi.org/10.1017/jfm.2022.737 ISSN 0022-1120 Source Journal of Fluid Mechanics, 949 Part of collection Institutional Repository Document type journal article Rights © 2022 W. Hu, S. Hickel, B.W. van Oudheusden Files PDF unsteady_mechanisms_in_sh ... g_step.pdf 9.97 MB Close viewer /islandora/object/uuid:a1ce3968-13dc-4dd7-b9f3-0a844162b6b9/datastream/OBJ/view