Nonequilibrium excitation of internal molecular degrees of freedom in the shock layer during hypersonic flight

Doroshenko, Vladimir M.; Koudriavtsev, N. N.; Smetanin, V. V.

doi:10.1007/bf01414636

Cited by 4 publications

(1 citation statement)

References 19 publications

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“…Nonequilibrium energy distributions of gases are not only commonly induced in gas dynamical processes involved in atmospheric (re)entry , and hypersonic cruise but also through the expanding flow within a regular nozzle. , From a thermal engineering point of view, knowing the heat loads acting on the solid structures is critical for reliably designing the respective structures. How these heat loads are affected by nonequilibrium, i.e., non-Boltzmann, energy distributions is not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Non-Boltzmann Heat Transfer between a Monatomic Gas and a Solid Nanostructure

Döntgen,

Heufer

2024

J. Phys. Chem. C

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The effect of non-Boltzmann energy distributions on the pressure, impingement rate, and heat flux of a monatomic gas in contact with a solid surface is investigated via theory and simulation. First, microcanonical formulations of the pressure, impingement rate, and heat flux are derived from first principles and integrated with prototypical energy distributions. Second, atomistic molecular dynamics simulations of an iron nanowire in a low-pressure argon atmosphere are used to test the non-Boltzmann heat flux theory. While pressure is found to be unaffected by the energy distribution of the gas, the impingement rate increases by up to 8.5% in the non-Boltzmann case. Most intriguingly, non-Boltzmann energy distributions can lead to a negative heat flux, meaning that heat flows from the cold solid to the hot gas. This non-Boltzmann heat flux effect is validated via the molecular dynamics simulations, and the solid is found to be 46% colder than the gas in the case of a hypothetical equilibrium for the upper-limiting non-Boltzmann energy distributions. The present fundamental findings provide novel insights into the properties of non-Boltzmann gases and improve the understanding of nonequilibrium dynamics.

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Section: Introductionmentioning

confidence: 99%

Non-Boltzmann Heat Transfer between a Monatomic Gas and a Solid Nanostructure

Döntgen,

Heufer

2024

J. Phys. Chem. C

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Modern gas-dynamic models in problems of super-and hypersonic aerodynamics and heat transfer

Tirskii¹

1993

Russ Phys J

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Theory and simulation of shock waves freely propagating through monoatomic non-Boltzmann gas

Döntgen

2024

Theor. Comput. Fluid Dyn.

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The effect of non-Boltzmann energy distributions on the free propagation of shock waves through a monoatomic gas is investigated via theory and simulation. First, the non-Boltzmann heat capacity ratio $$\gamma $$ γ , as a key property for describing shock waves, is derived from first principles via microcanonical integration. Second, atomistic molecular dynamics simulations resembling a shock tube setup are used to test the theory. The presented theory provides heat capacity ratios ranging from the well-known $$\gamma = 5/3$$ γ = 5 / 3 for Boltzmann energy-distributed gas to $$\gamma \rightarrow 1$$ γ → 1 for delta energy-distributed gas. The molecular dynamics simulations of Boltzmann and non-Boltzmann driven gases suggest that the shock wave propagates about 9% slower through the non-Boltzmann driven gas, while the contact wave appears to be about 4% faster if it trails non-Boltzmann driven gas. The observed slowdown of the shock wave through applying a non-Boltzmann energy distribution was found to be consistent with the classical shock wave equations when applying the non-Boltzmann heat capacity ratio. These fundamental findings provide insights into the behavior of non-Boltzmann gases and might help to improve the understanding of gas dynamical phenomena. Graphical abstract

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Nonequilibrium excitation of internal molecular degrees of freedom in the shock layer during hypersonic flight

Cited by 4 publications

References 19 publications

Non-Boltzmann Heat Transfer between a Monatomic Gas and a Solid Nanostructure

Non-Boltzmann Heat Transfer between a Monatomic Gas and a Solid Nanostructure

Modern gas-dynamic models in problems of super-and hypersonic aerodynamics and heat transfer

Theory and simulation of shock waves freely propagating through monoatomic non-Boltzmann gas

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