Search for a command to run...
Laminar–turbulent transition in shock wave–boundary-layer interactions (SWBLI) remains a critical challenge for hypersonic vehicle design, with strong implications for drag, heat transfer, and structural loads. Linear optimal perturbation analyses can isolate candidate instabilities, but identifying the full route to breakdown in SWBLI requires nonlinear optimisation.In this dataset, we characterise the optimal transition pathway in a globally stable yet convectively unstable Mach 2.15 oblique SWBLI using a nonlinear input–output optimisation framework based on the space–time spectral Navier–Stokes formulation (Poulain et al., Comput. Fluids, 2024). The nonlinear frequency-domain approach captures mean-flow distortion, resolves triadic energy transfers, and extracts intrinsic nonlinear stresses that activate additional instability mechanisms and ultimately lead to breakdown.We identify an efficient four-stage transition pathway: (1) optimal forcing of oblique first Mack mode waves at moderate frequencies; (2) non-linear self-interaction of counter-propagating Mack waves generating streamwise Görtler-like vortices in the reattachment region where streamline curvature peaks; (3) lift-up of streamwise velocity streaks by these vortices; and (4) sub-harmonic sinuous secondary instability leading to streak breakdown. Optimization across forcing amplitudes from infinitesimal to transitional levels yields quasi-invariant optimal forcing structures, demonstrating that exciting the oblique first Mack mode alone suffices to trigger the entire turbulent cascade. Parametric studies spanning frequency-wavenumber space and forcing configurations confirm this preferential pathway. By resolving non-linear energy transfers through a finite number of harmonics, this work establishes a computationally tractable framework for transition prediction and control strategy development in high-speed separated flows, bridging the gap between linear stability theory and fully turbulent simulation. Dataset structure tree_300x300dnc5_extraporder0_SBLI_freq2.0_beta45.0_A0.50e-5_Nt5_Nz17.zip | contains the forcing and response harmonics from the low forcing amplitude case (A=0.5e-5) computed by the non-linear optimisation. Forcing frequency = 2.0, spanwise wavenumber = 45.0. Number of harmonics N = 2, M = 4. Foricing configuration is fundamental.tree_300x300dnc5_extraporder0_SBLI_freq2.0_beta45.0_A3.00e-5_Nt5_Nz17.zip | contains the forcing and response harmonics from the high forcing amplitude case (A=3.0e-5) computed by the non-linear optimisation. Forcing frequency = 2.0, spanwise wavenumber = 45.0. Number of harmonics N = 2, M = 4. Foricing configuration is fundamental. tree_300x300dnc5_extraporder0_SBLI_freq2.0_beta45.0_A0.50e-5_Nt5_Nz17_forcing_superharmonic.zip | contains the forcing and response harmonics from the low forcing amplitude case (A=0.5e-5) computed by the non-linear optimisation. Forcing frequency = 2.0, spanwise wavenumber = 45.0. Number of harmonics N = 2, M = 4. Foricing configuration is super-harmonic. state_atcenter_mesh300_y300_xend195_angle308_T157_Mach215.dat | Mach 2.15 SWBLI base-flow computed for the shock angle 30.8deg. Eigenmodes.zip | complex eigenmode shapes computed from one globally stable (30.8deg) and one globally unstable (31.8deg) SWBLI base-flow. resolvent_angle308_T157_Mach215_mesh300_y300_xend195.zip | complex forcing and response mode shapes computed from linear resolvent analysis on the globally stable/convectively unstable (30.8deg) SWBLI base-flow.