Development of DSMC chemistry models for nitrogen collisions using accurate theoretical calculations

Neal Parsons, Tong Zhu, Deborah A. Levin, Adri C.T. Van Duin

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

Abstract

The Direct Simulation Monte Carlo (DSMC) method typically used for simulating hypersonic Earth re-entry flows requires accurate total collision and reaction cross sections. However, total cross sections are often determined from extrapolations of relatively lowtemperature viscosity data, so their reliability is unknown for the high temperatures observed in hypersonic re-entries. Existing DSMC reaction models accurately reproduce experimental equilibrium reaction rates, but the applicability of these rates to the strong thermal nonequilibrium observed in hypersonic shocks is unknown. For re-entry flows, these modeling issues are particularly relevant for nitrogen, the dominant species of air. Therefore, the Molecular Dynamics/Quasi-Classical Trajectories (MD/QCT) method is used to accurately compute collision and reaction cross sections for the N(4Su)-N2(1Σ+g) and N2(1Σ+g)-N2(1Σ+g) collision pairs for conditions expected in hypersonic shocks. For the N2-N2pair, a new potential energy surface is developed using the ReaxFF method, and the internal energy relaxation process is also studied usingMD/QCT. TheMD/QCT-computed reaction probabilities exhibited better physical behavior and predicted less dissociation than the baseline total collision energy (TCE) reaction model for strong nonequilibrium conditions expected in a shock. The MD/QCT reaction model was validated by good agreement of computed equilibrium reaction rates to experimental shock-tube data. The MD/QCT-computed total cross sections were found to agree well with established variable hard sphere (VHS) total cross sections. The MD/QCT total cross sections and reaction probabilities were then used in a DSMC computation of a 1D 5 km/s shock. The DSMC results using the MD/QCT models predicted approximately 7.5% less dissociation and a slightly thicker shock than those using baseline TCE/VHS models.

Original languageEnglish (US)
Title of host publication52nd Aerospace Sciences Meeting
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
ISBN (Electronic)9781624102561
StatePublished - Jan 1 2014
Externally publishedYes
Event52nd Aerospace Sciences Meeting 2014 - National Harbor, United States
Duration: Jan 13 2014Jan 17 2014

Publication series

Name52nd Aerospace Sciences Meeting

Other

Other52nd Aerospace Sciences Meeting 2014
CountryUnited States
CityNational Harbor
Period1/13/141/17/14

Fingerprint

Hypersonic aerodynamics
Molecular dynamics
Trajectories
Reentry
Nitrogen
Reaction rates
Potential energy surfaces
Shock tubes
Relaxation processes
Extrapolation
Monte Carlo methods
Earth (planet)
Monte Carlo simulation
Viscosity
Air
Temperature

ASJC Scopus subject areas

  • Aerospace Engineering

Cite this

Parsons, N., Zhu, T., Levin, D. A., & Van Duin, A. C. T. (2014). Development of DSMC chemistry models for nitrogen collisions using accurate theoretical calculations. In 52nd Aerospace Sciences Meeting (52nd Aerospace Sciences Meeting). American Institute of Aeronautics and Astronautics Inc..

Development of DSMC chemistry models for nitrogen collisions using accurate theoretical calculations. / Parsons, Neal; Zhu, Tong; Levin, Deborah A.; Van Duin, Adri C.T.

52nd Aerospace Sciences Meeting. American Institute of Aeronautics and Astronautics Inc., 2014. (52nd Aerospace Sciences Meeting).

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

Parsons, N, Zhu, T, Levin, DA & Van Duin, ACT 2014, Development of DSMC chemistry models for nitrogen collisions using accurate theoretical calculations. in 52nd Aerospace Sciences Meeting. 52nd Aerospace Sciences Meeting, American Institute of Aeronautics and Astronautics Inc., 52nd Aerospace Sciences Meeting 2014, National Harbor, United States, 1/13/14.
Parsons N, Zhu T, Levin DA, Van Duin ACT. Development of DSMC chemistry models for nitrogen collisions using accurate theoretical calculations. In 52nd Aerospace Sciences Meeting. American Institute of Aeronautics and Astronautics Inc. 2014. (52nd Aerospace Sciences Meeting).
Parsons, Neal ; Zhu, Tong ; Levin, Deborah A. ; Van Duin, Adri C.T. / Development of DSMC chemistry models for nitrogen collisions using accurate theoretical calculations. 52nd Aerospace Sciences Meeting. American Institute of Aeronautics and Astronautics Inc., 2014. (52nd Aerospace Sciences Meeting).
@inproceedings{f75513f36f7d47b79ccf8aee21127204,
title = "Development of DSMC chemistry models for nitrogen collisions using accurate theoretical calculations",
abstract = "The Direct Simulation Monte Carlo (DSMC) method typically used for simulating hypersonic Earth re-entry flows requires accurate total collision and reaction cross sections. However, total cross sections are often determined from extrapolations of relatively lowtemperature viscosity data, so their reliability is unknown for the high temperatures observed in hypersonic re-entries. Existing DSMC reaction models accurately reproduce experimental equilibrium reaction rates, but the applicability of these rates to the strong thermal nonequilibrium observed in hypersonic shocks is unknown. For re-entry flows, these modeling issues are particularly relevant for nitrogen, the dominant species of air. Therefore, the Molecular Dynamics/Quasi-Classical Trajectories (MD/QCT) method is used to accurately compute collision and reaction cross sections for the N(4Su)-N2(1Σ+g) and N2(1Σ+g)-N2(1Σ+g) collision pairs for conditions expected in hypersonic shocks. For the N2-N2pair, a new potential energy surface is developed using the ReaxFF method, and the internal energy relaxation process is also studied usingMD/QCT. TheMD/QCT-computed reaction probabilities exhibited better physical behavior and predicted less dissociation than the baseline total collision energy (TCE) reaction model for strong nonequilibrium conditions expected in a shock. The MD/QCT reaction model was validated by good agreement of computed equilibrium reaction rates to experimental shock-tube data. The MD/QCT-computed total cross sections were found to agree well with established variable hard sphere (VHS) total cross sections. The MD/QCT total cross sections and reaction probabilities were then used in a DSMC computation of a 1D 5 km/s shock. The DSMC results using the MD/QCT models predicted approximately 7.5{\%} less dissociation and a slightly thicker shock than those using baseline TCE/VHS models.",
author = "Neal Parsons and Tong Zhu and Levin, {Deborah A.} and {Van Duin}, {Adri C.T.}",
year = "2014",
month = "1",
day = "1",
language = "English (US)",
series = "52nd Aerospace Sciences Meeting",
publisher = "American Institute of Aeronautics and Astronautics Inc.",
booktitle = "52nd Aerospace Sciences Meeting",

}

TY - GEN

T1 - Development of DSMC chemistry models for nitrogen collisions using accurate theoretical calculations

AU - Parsons, Neal

AU - Zhu, Tong

AU - Levin, Deborah A.

AU - Van Duin, Adri C.T.

PY - 2014/1/1

Y1 - 2014/1/1

N2 - The Direct Simulation Monte Carlo (DSMC) method typically used for simulating hypersonic Earth re-entry flows requires accurate total collision and reaction cross sections. However, total cross sections are often determined from extrapolations of relatively lowtemperature viscosity data, so their reliability is unknown for the high temperatures observed in hypersonic re-entries. Existing DSMC reaction models accurately reproduce experimental equilibrium reaction rates, but the applicability of these rates to the strong thermal nonequilibrium observed in hypersonic shocks is unknown. For re-entry flows, these modeling issues are particularly relevant for nitrogen, the dominant species of air. Therefore, the Molecular Dynamics/Quasi-Classical Trajectories (MD/QCT) method is used to accurately compute collision and reaction cross sections for the N(4Su)-N2(1Σ+g) and N2(1Σ+g)-N2(1Σ+g) collision pairs for conditions expected in hypersonic shocks. For the N2-N2pair, a new potential energy surface is developed using the ReaxFF method, and the internal energy relaxation process is also studied usingMD/QCT. TheMD/QCT-computed reaction probabilities exhibited better physical behavior and predicted less dissociation than the baseline total collision energy (TCE) reaction model for strong nonequilibrium conditions expected in a shock. The MD/QCT reaction model was validated by good agreement of computed equilibrium reaction rates to experimental shock-tube data. The MD/QCT-computed total cross sections were found to agree well with established variable hard sphere (VHS) total cross sections. The MD/QCT total cross sections and reaction probabilities were then used in a DSMC computation of a 1D 5 km/s shock. The DSMC results using the MD/QCT models predicted approximately 7.5% less dissociation and a slightly thicker shock than those using baseline TCE/VHS models.

AB - The Direct Simulation Monte Carlo (DSMC) method typically used for simulating hypersonic Earth re-entry flows requires accurate total collision and reaction cross sections. However, total cross sections are often determined from extrapolations of relatively lowtemperature viscosity data, so their reliability is unknown for the high temperatures observed in hypersonic re-entries. Existing DSMC reaction models accurately reproduce experimental equilibrium reaction rates, but the applicability of these rates to the strong thermal nonequilibrium observed in hypersonic shocks is unknown. For re-entry flows, these modeling issues are particularly relevant for nitrogen, the dominant species of air. Therefore, the Molecular Dynamics/Quasi-Classical Trajectories (MD/QCT) method is used to accurately compute collision and reaction cross sections for the N(4Su)-N2(1Σ+g) and N2(1Σ+g)-N2(1Σ+g) collision pairs for conditions expected in hypersonic shocks. For the N2-N2pair, a new potential energy surface is developed using the ReaxFF method, and the internal energy relaxation process is also studied usingMD/QCT. TheMD/QCT-computed reaction probabilities exhibited better physical behavior and predicted less dissociation than the baseline total collision energy (TCE) reaction model for strong nonequilibrium conditions expected in a shock. The MD/QCT reaction model was validated by good agreement of computed equilibrium reaction rates to experimental shock-tube data. The MD/QCT-computed total cross sections were found to agree well with established variable hard sphere (VHS) total cross sections. The MD/QCT total cross sections and reaction probabilities were then used in a DSMC computation of a 1D 5 km/s shock. The DSMC results using the MD/QCT models predicted approximately 7.5% less dissociation and a slightly thicker shock than those using baseline TCE/VHS models.

UR - http://www.scopus.com/inward/record.url?scp=84938398262&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84938398262&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:84938398262

T3 - 52nd Aerospace Sciences Meeting

BT - 52nd Aerospace Sciences Meeting

PB - American Institute of Aeronautics and Astronautics Inc.

ER -