Abstract
This paper analyzes the effects of the full diffusion model derived from the Chapman-Enskog theory on hypersonic flows. This model describes the mass diffusion flux as a superimposition of diffusion due to mole fraction gradients (Fickian term), the temperature gradient (Soret term), and the pressure gradient. Furthermore, the heat flux includes an additional term (Dufour term) that represents the contribution of the species mole fractions to energy transport. We implement the Stefan-Maxwell linear systems for the transport properties into the US3D compressible Navier-Stokes solver and present a parametric study on the contribution of these diffusion terms, which are usually neglected in hypersonic simulations. Focusing on the regions characterized by strong thermochemical non-equilibrium, such as the post-shock and the near-wall areas, we study a flow around a sphere and a sphere-cone with a catalytic wall boundary condition using different catalytic efficiencies, r. We observe that the molecular species mass fractions profiles show peculiar behaviors at the shock when the complete diffusion terms are included. Moreover, these terms also affect the near-wall region when the catalytic wall boundary condition with null or very low values of r is applied. Based on these results, we repeat the analysis of the cylinder case with different free stream velocities shown in a previous study and compare the solutions with the DSMC simulation. We observe that the behavior at the shock in the CFD solutions when solving the full diffusion model is also present in the DSMC solutions. Furthermore, the trend of the DSMC results is predicted better by the full diffusion model than with the Fickian term only. Thus, the Soret and the pressure gradient terms in the mass conservation equation, and Dufour term in the energy equation play a significant role in the area characterized by steep gradients identifying trends that are not captured by the diffusion model composed of the Fickian and the Fourier contribution.
Original language | English (US) |
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Title of host publication | AIAA SciTech Forum and Exposition, 2023 |
Publisher | American Institute of Aeronautics and Astronautics Inc, AIAA |
ISBN (Print) | 9781624106996 |
DOIs | |
State | Published - 2023 |
Event | AIAA SciTech Forum and Exposition, 2023 - Orlando, United States Duration: Jan 23 2023 → Jan 27 2023 |
Publication series
Name | AIAA SciTech Forum and Exposition, 2023 |
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Conference
Conference | AIAA SciTech Forum and Exposition, 2023 |
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Country/Territory | United States |
City | Orlando |
Period | 1/23/23 → 1/27/23 |
Bibliographical note
Publisher Copyright:© 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.