Impact of fundamental molecular kinetics on macroscopic properties of high-enthalpy flows: The case of hypersonic atmospheric entry

A state-to-state approach and GPU processors are used to find the nonequilibrium vibrational distributions of O 2 and N 2 in a hypersonic flow past a sphere. Thermochemical nonequilibrium is one of the most challenging issues when dealing with hypersonic flows experienced by objects (space vehicles, meteoroids, space debris) at atmospheric entry. The case of a hypersonic flow past a sphere is considered as a test model for systems in strong chemical and thermal nonequilibrium conditions, mimicking the extreme environment experienced by objects entering a planetary atmosphere. The problem has been studied using the state-to-state approach, calculating directly the distribution of vibrational levels of O 2 and N 2 , together with the flow field, including also viscous effects. Nonequilibrium distributions are observed and the results have been compared with macroscopic experimental data, showing that the state-to-state model is able to provide better capabilities for predicting experimental results than the traditional multitemperature approach. The use of graphics processing units allowed us to obtain these results in a two-dimensional configuration, opening additional perspectives in the investigation of reacting flows.