State-to-state collision integrals and transport coefficients in oxygen mixtures
1St Petersburg University, 7-9 Universitetskaya Embankment, St Petersburg 199034, Russia.
The Journal of Chemical Physics
|February 23, 2026
Summary
Accurate transport coefficients are crucial for high-speed flight. This study reveals vibrational excitation significantly impacts collision integrals and transport properties, especially at high temperatures, necessitating advanced models for accurate predictions.
Area of Science:
- Aerothermodynamics
- Chemical Kinetics
- Computational Fluid Dynamics
Background:
- Accurate transport coefficients are essential for modeling high-speed flight and atmospheric reentry.
- Existing models often lack precision at extreme temperatures and for vibrationally excited molecules.
Purpose of the Study:
- To calculate vibrationally state-resolved transport collision integrals for O2-O and O2-O2 systems.
- To provide a comprehensive dataset for these systems.
- To analyze the impact of vibrational excitation on transport properties and assess existing models.
Main Methods:
- Utilized the quasi-classical trajectory method.
- Employed high-accuracy ab initio potential energy surfaces.
- Applied a state-to-state kinetic framework.
Main Results:
- Vibrational excitation significantly influences collision integrals and transport coefficients, with effects amplified at high temperatures.
- Collision integrals varied up to 50% between ground and excited vibrational states.
- Deviations from the Parker model were observed for rotational relaxation times.
Conclusions:
- Traditional phenomenological models underestimate shear viscosity and thermal conductivity above 10,000 K in molecule-dominated mixtures.
- These models overestimate bulk viscosity across all temperatures.
- The study provides high-precision data and clarifies model applicability limits for computational fluid dynamics.
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