Mathematics

Flight systems operating at high speeds in the denser parts of the atmosphere can be quite different: aircraft, rockets or reentry vehicles, but they are all enveloped by turbulent, hot, highly compressible flow with possible chemical non-equilibrium. These effects become dominant in the proximity of the solid surfaces and drastically affect the mechanical and thermal loads on the vehicle. For this reason, a detailed description of the flow dynamics is essential to inform design choices.In the first part of this seminar, a series of Direct Numerical Simulations of turbulent boundary layers from supersonic to hypersonic conditions will be discussed with particular attention to the interplay between the Mach number and surface temperature effects on the flow dynamics. These simulations consider the gas to be in the calorically perfect state, which is a good approximation for large portions of the reentry trajectories.The second part of the discussion will focus on modeling aspects of hypersonic turbulent boundary layers at suborbital enthalpies, in which thermochemical processes become relevant and can affect the structural integrity of the flight system. A novel formulation of a wall model based on the inverse-velocity transformation is presented and preliminary results are shown.