Separation Mitigation over a Modified Boeing Speed Bump using Multi-stable Metamaterial

This experimental study aims to mitigate turbulent boundary layer (TBL) separation over a modified Gaussian Speed bump at Reynolds numbers based on bump height Re_h, between 1.3 x 10⁴ to 8.8 x 10⁴. To achieve separation mitigation, multi-stable metamaterials are integrated on the downstream side of the bump where the TBL separates. Vortex generators will be triggered by the pressure difference between the upstream and downstream regions of the bump. The bump geometry has an aspect ratio of w/h= 6.65, where w is the width of the bump in the spanwise direction and h represents its height. This talk will present a characterization of the surface stresses and separation structure observed on the bump, along with preliminary insights on the interaction with the multi-stable vortex generators. The experimental results will be compared to different bumps of interest in the fluid dynamics community, such as the BeVERLI hill bump with w/h = 5 (Gargiulo et al, 2020) and the Gaussian Speed bump with w/h = 11.8 (Owens, 2020). Oil flow visualizations will be presented of the separation structure downstream of the bump, where nodes, saddle points, and foci will be identified. Statistics and spectral content of the surface pressure on the upstream and downstream surfaces of the bump will be presented. The work will provide insight into the forces that can be used to trigger metamaterial control, and preliminary work on the coupling to vortex generators will be presented.

This material is based upon work supported by the Air Force Office of Scientific Research under award number FA9550-23-1-0299 and the Office of Naval Research N00014-25-1-2255.