Objective molecular dynamics of dissociating nitrogen under high temperature conditions

Gunjan Pahlani, Erik Torres, Thomas E. Schwartzentruber, Richard D. James

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


We present a novel method of Objective Molecular Dynamics (OMD) for the study of air chemistry at high temperatures far-from-equilibrium flows commonly encountered in hypersonic conditions. The method gives a way of simulating a three parameter family of homogeneous incompressible, and a nine parameter family of general compressible, unsteady flows without incurring boundary effects, which is ideal for extracting bulk properties of the system. Besides the usual advantage of molecular dynamics simulations of relying only on a potential energy surface, OMD has an additional advantage. Here, only a finite number of atoms are simulated, and motions of all the other atoms (typically infinitely many) are given by applying an isometry group to the simulated atoms. All atoms, simulated and nonsimulated, satisfy exactly the equations of molecular dynamics for their forces. In this work, we use OMD to simulate an inviscid flow of homoenergetic compression of dissociating nitrogen gas and report the non-Boltzmann effects of overpopulation and underpopulation of the vibrational energy distribution. We also compare evolution of gas in an adiabatic reactor simulated by using OMD to those simulated by a different modeling approach of Direct Molecular Simulation (DMS) for non-equilibrium initial conditions.

Original languageEnglish (US)
Title of host publicationAIAA Scitech 2021 Forum
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
Number of pages10
ISBN (Print)9781624106095
StatePublished - 2021
EventAIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2021 - Virtual, Online
Duration: Jan 11 2021Jan 15 2021

Publication series

NameAIAA Scitech 2021 Forum


ConferenceAIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2021
CityVirtual, Online

Bibliographical note

Funding Information:
G. Pahlani and R.D. James acknowledge funding from the Multidisciplinary Research Program of the University Research Initiative (MURI) under Grant No. FA9550-18-1-0095 and a Vannevar Bush Faculty Fellowship. T. E. Schwartzentruber and E. Torres acknowledges funding from NASA under Grant 80NSSC20K1061.

Publisher Copyright:
© 2021, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.


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