Simulations of Boundary-Layer Response to Laser-Generated Disturbances at Mach 6

A finite volume Navier-Stokes code was used to simulate the interaction of a laser-induced disturbance with a conical boundary layer at Mach 5.85. The simulations start 0.2 mu s after an optically induced breakdown that generates an initial disturbance. The initial disturbance was determined from Taylor's intense explosion similarity law and this disturbance is imposed into the flowfield of a 7 deg half-angle cone. The initial disturbance parameters, such as energy, were obtained from comparisons to experimental data. The disturbance was imposed some distance above the model and the boundary layer, so that mainly the propagating shock wave interacts with the boundary layer. This interaction results in the formation of a second-mode wave packet, and its generation and development are described. Also, comparisons to experimental data and to results of the linear stability theory are given. Furthermore, some disturbance parameters were varied, such as released energy or the number of laser pulses.