High-resolution Direct Numerical Simulations (DNS) were carried out to identify the dominant nonlinear mechanisms of three-dimensional wave packets in a Mach 10 boundary layer on a 7◦ half-angle straight (right) cone with a “sharp” nose tip at zero angle of attack. Towards this end, nonlinear wave packets were generated with a short-duration pulse. For these simulations the same cone geometry as in experiments at the Arnold Engineering Development Complex (AEDC) Hypervelocity Wind Tunnel No. 9 (T9) were used. The simulations were carried out for hypothetical flight conditions while matching the Mach number and the unit Reynolds number of the wind tunnel experiments. The wave packet simulations were carried out into the nonlinear transition stages in order to extract the dominant nonlinear mechanisms for the respective flow conditions. The computational domain covered a large extent of the cone in the azimuthal direction to allow for a wide range of azimuthal wavenumbers (kc ).