Numerical simulations of Controlled transition for a sharp circular cone at Mach 8

The linear and nonlinear development of disturbance waves in an axisymmetric boundary layer on a sharp circular cone at Mach 8 are investigated by numerical solution of the full 3D, time dependent, compressible Navier-Stokes equations. Disturbances are introduced by wall-normal blowing and suction near the upstream boundary of the computational domain. Small amplitude disturbances are introduced to study their linear stability behavior and the results are compared with Linear Stability Theory (LST) for validation. These results are also used to guide parameter selection for simulations of nonlinear transition phenomena. In particular, for simulations with large amplitude 2D disturbances, fundamental resonance can be observed. This resonance leads to nonlinear amplification of 3D modes and the classical aligned A-vortex pattern as the boundary layer begins to transition to turbulence. Simulations of oblique breakdown are also performed and the two transition mechanisms are compared.