High-Resolution Simulations of Transitional Triple-Point Shock Interactions

This work concerns the evolution of the Ritchmyer-Meshkov instability (RMI) in a rather unconventional setting: a 3D periodic extension of the triple point canonical problem. The time frame of the study includes reshock of the interface, making this a case which hasn't been studied before. The nature of the transition to turbulence is particularly investigated, which is dependent on the initial conditions, shock induced transition, and other instability mechanisms such as secondary baroclinic instability. These aspects were examined using an ensemble of configurations of the problem at various resolutions for different initial conditions, along with an appropriate mesh convergence study. In particular, the initial conditions were dictated in the form of interfacial perturbations made up of a superposition of Fourier modes. It was found that perturbations dominated by low wavenumber content showed a ballistic scaling at early times and led to greater turbulent kinetic energy production at late times. However, the turbulent kinetic energy spectra still showed prominent traces of the initial conditions. Perturbations containing a broadband content on the other hand exhibit a diffusive scaling at early times, and the spectral content at late times resembles that of isotropic turbulence.