Sergio Pirozzoli

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We develop a reduced-order model for large-scale unsteadiness (vortex shedding) in a two-dimensional diffuser and use the model to show how periodic mass injection near the separation point reduces stagnation pressure loss. The model estimates the characteristic frequency of vortex shedding and stagnation pressure loss by accounting for the accumulated(More)
Direct numerical simulation is used to investigate the effect of compressibility on roughness-induced boundary layer transition. Computations are performed in both the low-and the high-speed regime (at free-stream Mach number M e = 2) for an isolated three-dimensional element with cubic shape and for two-dimensional roughness strips. For each configuration(More)
We develop numerical boundary conditions for the compressible Navier–Stokes equations based on a generalized relaxation approach (GRCBC), which hinges on locally one-dimensional characteristic projection at the computational boundaries, supplemented with available information from the flow exterior. The basic idea is to estimate the amplitude of incoming(More)
The laminar-to-turbulent transition of boundary layers induced by isolated three-dimensional roughness elements is analyzed by mining a direct numerical simulation database, which covers the variation of many physical parameters, including Mach and Reynolds numbers, and obstacle shape and size. We find that the transition process is approximately controlled(More)