Direct simulation of rovibrational excitation and dissociation in molecular nitrogen using an ab initio potential energy surface

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Scopus citations

Abstract

We present an atomic-level study of vibrational excitation and chemical dissociation in molecular nitrogen at high temperature. The computational techniques, quasiclassical trajectory calculations (QCT) and classical trajectory calculation direct simulation Monte Carlo (CTC DSMC), solely rely on the specification of a highly accurate ab initio surface for N2-N2 interactions. We show that the simulations accurately reproduce the vibrational relaxation times obtained from the Millikan-White correlation and further support existing high-temperature corrections. Using both QCT and CTC DSMC methods with the same PES, we show that dissociation proceeds 4 to 5 times faster under equilibrium conditions compared to quasi-steady-state nonequilibrium conditions. At high translational energies (20,000 K and 30,000 K), the overall vibrational energy ladder is depleted, and dissociation proceeds at a rate approximately corresponding to a lower vibrational temperature. Conversely, at lower energies (10,000 K), almost no dissociation occurs from low-lying vibrational energy states. In this case, even a slight depletion of the upper-level vibrational energy states, which preferentially dissociate and are not rapidly re-populated due to slow bound-bound energy transfer mechanisms, causes a remarkable reduction of the dissociation rate. The ab initio CTC DSMC method is able to directly simulate rovibrational excitation and dissociation processes without computing the large number of cross-sections required by a state-resolved approach, and can be used directly to form new CFD models.

Original languageEnglish (US)
Title of host publication53rd AIAA Aerospace Sciences Meeting
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624103438
DOIs
StatePublished - 2015
Event53rd AIAA Aerospace Sciences Meeting, 2015 - Kissimmee, United States
Duration: Jan 5 2015Jan 9 2015

Publication series

Name53rd AIAA Aerospace Sciences Meeting

Other

Other53rd AIAA Aerospace Sciences Meeting, 2015
Country/TerritoryUnited States
CityKissimmee
Period1/5/151/9/15

Bibliographical note

Funding Information:
The research is supported by Air Force Office of Scientific Research (AFOSR) under Grant No. FA9550-10-1-0563. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the AFOSR or the U.S. Government. Jason D. Bender was supported in this work by the Department of Energy Computational Science Graduate Fellowship (DOE CSGF) under grant number DE-FG02-97ER25308.

Publisher Copyright:
© 2015 by Valentini, Schwartzentruber, Bender, Nompelis, and Candler.

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