Numerical domain

The computed configuration is the experimental 2D nozzle previously de­scribed. The numerical domain was however extended 70mm upstream and 164mm downstream of the bump in order to avoid numerical interaction with the boundaries. Steady state simulations were performed on both 2D and 3D structured H-grids in order to achieve a good understanding of the mean ft>w structures. The respectively meshes comprise 150×84 and 150x84x35 nodes with adapted grid density both around the shock location and in upper, lower and side wall BLs (containing respectively 33, 28 and 26 nodes). Unsteady simulations were however only performed on the 2D mesh due to computation time restriction. Both RANS and Euler unsteady computations were performed for comparison purposes.

1.4 Steady flow conditions

For RANS computations, the fhid is modelled as a viscous perfect gas. The specific heat ratio equals k=1.4 and the perfect gas constant is R=287 J/kg/K. The laminar dynamic viscosity and the thermal conductibility are assumed con­stant and respectively equal ^=1.81 10-5 kg/m/s and k=2.54 10-2 m. kg/K/s3. The inlet conditions in the free stream are such that the stagnation pressure, pmiet, and the stagnation temperature, Ttmlet, equal respectively 160kPa and 303K. A fully developed 7mm thick BL profile computed over a flat duct is specified as inlet condition. The outlet static pressure was adjusted in order to match the experimental shock configuration. The numerical operating condi­tions are summarized in table 2.