Simulation of Polyatomic Gas Cloud Expansion under Pulsed Laser Ablation by Model Boltzmann Equation

Anna A. Frolova

doi:10.14529/jsfi230104

Authors

Anna A. Frolova Federal Research Center “Computer Science and Control” of the Russian Academy of Sciences, Moscow, Russia

DOI:

https://doi.org/10.14529/jsfi230104

Keywords:

model kinetic equations, rotational degrees of freedom, pulsed laser ablation, non-stationary problems

Abstract

Polyatomic gas cloud expansion into vacuum under pulsed laser ablation is studied on the basis of one-dimensional model kinetic equation. To account for the influence of internal energy on the vapor-gas cloud parameters (density, temperature, and velocity) a model kinetic equation of the BGK-type is applied, which considers the energy exchange using a two-temperature model. In this approach, the collision integral is approximated by the sum of two terms corresponding to elastic (translational relaxation) and inelastic (rotational relaxation) collisions. Note that the vibrational energy is not taken into account in this paper. The independence of the differential part of transfer equation from the rotational energy makes it possible to reduce the equation to a system with two functions. A comparison of the gas flow macroparameters obtained by the kinetic equations and the DSMC is carried out. The influence of the number of rotational degrees of freedom on the evolution of average temperature and on the gas parameters is shown. The calculations are performed on non-uniform grids in the phase space with global dynamic velocity mesh adaptation to suppress the “ray effect”.

References

Bykov, N.Y., Bulgakova, N.M., Bulgakov, A.V., Loukianov, G.A.: Pulsed laser ablation of metals in vacuum: DSMC study versus experiment. Appl. Phys. A. 79, 1097–1100 (2004). https://doi.org/10.1007/s00339-004-2654-6

Morozov, A.A., Mironova, M.L.: Numerical analysis of time-of-flight distributions of neutral particles for pulsed laser ablation of binary substances into vacuum. Appl. Phys. A 123(12), article 783 (2017). https://doi.org/10.1007/s00339-017-1400-9

Morozov, A.A.: Analysis of time-of-flight distributions under pulsed laser ablation in vacuum based on the DSMC calculations. Appl. Phys. A 111(4), 1107–1111 (2013). https://doi.org/10.1007/s00339-012-7325-4

Itina, T.E., Hermann, J., Delaporte, P., Sentis, M.: Laser-generated plasma plume expansion: Combined continuous-microscopic modeling. Physical Review E 66, 066406 (2002). https://doi.org/10.1103/PhysRevE.66.066406

Morozov, A.A., Frolova, A.A., Titarev, V.A.: On different kinetic approaches for computing planar gas expansion under pulsed evaporation into vacuum. Phys. Fluids (2020). https://doi.org/10.1063/5.0028850

Titarev, V.A., Morozov, A.A.: Arbitrary Lagrangian-Eulerian discrete velocity method with application to laser-induced plume expansion. Applied Mathematics and Computation 429, 127241 (2022). https://doi.org/10.1016/j.amc.2022.127241

Morozov, A.A.: Dynamics of pulsed expansion of polyatomic gas cloud: Internal translational

energy transfer contribution. Phys. Fluids 19(8), 087101 (2007). https://doi.org/10.1063/1.2754347

Morozov, A.A.: Analytical model for polyatomic gas expansion under pulsed. Physics of Fluids 20, 027103 (2008). http://doi.org/10.1063/1.2841624

Titarev, V.A., Frolova, A.A.: Application of Model Kinetic Equations to Calculations of Super- and Hypersonic Molecular Gas Flows. Fluid Dynamics 53(4), 536–551 (2018). https://doi.org/10.1134/S0015462818040110

Kolobov, V.I., Arslanbekov, R.R., Aristov, V.V., et al.: Unified Solver for Rarified and Continuum Flows with Adaptive Mesh and Algorithm Refinement. J. Comp. Phys. 223, 589–608 (2007). https://doi.org/10.1016.j.jcp.2006.09.021