This work presents a comparison of the non-equilibrium energy transfer and dissociation of nitrogen molecules using two different approaches: the Direct Molecular Simulation (DMS) method and the State-to-State (StS) method. The two methods are used to study the thermochemical relaxation in a zero-dimensional isochoric and isothermal reactor. Both methods make use of the same potential energy surface (PES) for the N2(1Σ+g) − N(4Su) system taken from the NASA Ames quantum chemistry database. The DMS method is a stochastic method, which relies on sampling scattering calculations to directly determine the non-equilibrium evolution of a gas. In contrast, the StS model is a deterministic approach which relies on a complete kinetic database to directly solve the master equation for each internal energy state. The analysis reveals several differences between the two approaches. First, because of the reliance on sampling in the DMS method, accurately predicting the population of high energy states is difficult and subject to statistical error. Moreover, the DMS method does not map post-collision energies back to discrete states, meaning that distribution of states across energy is much smoother with this method. Despite the differences observed in the microscopic distribution, the macroscopic properties predicted by both methods agree well during both energy transfer and dissociation.
|Original language||English (US)|
|Title of host publication||AIAA Aerospace Sciences Meeting|
|Publisher||American Institute of Aeronautics and Astronautics Inc, AIAA|
|State||Published - 2018|
|Event||AIAA Aerospace Sciences Meeting, 2018 - Kissimmee, United States|
Duration: Jan 8 2018 → Jan 12 2018
|Name||AIAA Aerospace Sciences Meeting, 2018|
|Other||AIAA Aerospace Sciences Meeting, 2018|
|Period||1/8/18 → 1/12/18|
Bibliographical noteFunding Information:
the AFOSR or the US government. Mr. M. Grover was supported by the Doctoral Dissertation Fellowship at the University of Minnesota.
The authors would like to thank David Schwenke and Richard Jaffe from NASA Ames Research Center for their helpful discussions. Dr. M. Panesi was supported by the Air Force Office of Scientific Research Young Investigators Program FA9550-15-1-0132. Ms. R. Macdonald was supported by the Department of Defense (DoD) through the National Defense Science and Engineering Graduate (NDSEG) Fellowship. Dr. T. Schwartzentruber is supported by Air Force Office of Scientific Research (AFOSR) under Grant No. FA9550-16-1-0161. 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