DSMC analysis of molecular beam experiments for oxidation of carbon based Ablators

Krishnan Swaminathan-Gopalan, Arnaud Borner, Kelly A. Stephaniz, Vanessa J. Murray, Savio Poovathingal, Timothy K. Minton, Nagi N. Mansour

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

7 Scopus citations


Direct simulation Monte Carlo (DSMC) is used to perform simulations of molecular beam scattering experiments of a hyperthermal O/O2 beam striking a vitreous carbon surface. The current DSMC surface reaction model specifies the probabilities and characteristic frequencies associated with adsorption, desorption, Langmuir-Hinshelwood, and prompt thermal mechanisms according to reaction rate constants, sticking coefficients, and surface coverage. In addition to the macroscopic information (reaction mechanisms, rate constants, etc.), this DSMC model also includes microscopic information regarding detailed scattering of ablation products from a carbon surface (including sticking coefficients, desorption barriers, angular scattering, etc.). This DSMC solver is used to perform simulations of the molecular beam scattering from vitreous carbon with substrate temperatures ranging from 550-2000 K. Detailed analysis of the experimental time-of-flight (TOF) and angular distributions is used to propose modifications to the carbon surface oxidation model developed by Poovathingal et al., in order to better capture the features of the TOF distribution. We demonstrate that this revised model captures features in the TOF distributions, including the long tail in the CO distribution that indicates a slow CO production process and the fast component in the O distribution that corresponds to impulsively scattered and thermally desorbed O atoms, which were not captured with the previous model. Comparisons between the simulated (DSMC) and experimental TOF distributions, angular distributions, and relative product fluxes show excellent agreement. The resulting DSMC model is provided describing the detailed scattering information of the products, and the probabilities and characteristic frequencies of surface reactions based on finite rates.

Original languageEnglish
Title of host publicationAIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting
ISBN (Electronic)9781624104473
StatePublished - 2017
Event55th AIAA Aerospace Sciences Meeting - Grapevine, United States
Duration: Jan 9 2017Jan 13 2017

Publication series

NameAIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting


Conference55th AIAA Aerospace Sciences Meeting
Country/TerritoryUnited States

Bibliographical note

Funding Information:
This work was performed under the Entry System Modeling Project (M. J. Wright Project Manager) at the NASA Game Changing Development (GCD) Program and supported by NASA Grants NNX15AU92F and NNX15AD77G.

Publisher Copyright:
© 2017 by the American Institute of Aeronautics and Astronautics, Inc.

ASJC Scopus subject areas

  • Aerospace Engineering


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