Hypersonic Boundary Layers: Oxygen Recombination on SiO2 Starting from Ab Initio Coefficients

摘要

InN A recent work [1], different models of diffusive qwRec andnFourier qF components of the heat transfer on a body undernhypersonic nitrogen flow conditions have been investigated. Innparticular, the ground vibrational state (GVS)model assumes that allnthe molecules desorbed from the surface are in their ground vibra-ntional state, the last vibrational state (LVS) model assumes that thendesorbed molecules are in the last vibrational level of the vibrationalnladder, and the more realistic diffuse vibrational state (DVS) modelnconsiders a spread of the recombination energy in the wholenmolecular ladder. The results for the N2-N mixture strongly dependnon the used model as well as on the inclusion of the state-to-statenkinetics in gas phase. In particular, the importance of gas surfacenmolecular dynamics (MD) in deriving the state-selected recom-nbination coefficients as a tool to pass from a phenomenological to anquantitative description of the phenomenon has been stressed. Thenaim of this Note is to use recent molecular dynamic calculations ofnstate-selected recombination coefficients of atomic oxygen on anu0005-cristobalite surface for assessing the qualitative results discussednin [1], even if in the case of a different mixture, i.e., O2-O instead ofnN2-N. The new state-selected recombination coefficients representnan improvement with the respect of the corresponding ones reportednin [2] for a surface temperature of 1000 K and a novelty for a surfacentemperature of 1600 K.