Investigating the effects of vibrational non-equilibrium on the local flow topologies of turbulent boundary layer flows

In hypersonic flows, the multiatomic molecules undergo a state of vibrational non-equilibrium when their vibrational energy modes may not be in equilibrium with their translational-rotational energy modes. This vibrational non-equilibrium state significantly affects the dynamics of the velocity gradient tensor. In this study, we investigate the effect of vibrational non-equilibrium on velocity gradient structures and fluid flow topologies in compressible turbulent boundary layer (TBL) flows. To clearly investigate the effect of vibrational nonequilibrium on local flow topologies, we performed the temporal direct numerical simulations (TDNS) of a compressible turbulent boundary layer with and without having vibrational nonequilibrium effects. We further explore the effect of varying initial non-dimensional parameters governing the dynamics of vibrationally excited TBL flows, such as the free stream Mach number, the momentum-thickness-based Reynolds number, the Damköhler number, and the ratio of the mean vibrational temperature to the mean temperature. The insights gained from this study will be communicated during the final presentation.