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Hi everyone. In the Millikan White class, the computation of the vibrational relaxation time is done according to Eq. (55) of (Gnoffo et. al., 1989). However, according to Eq. (35) in (Lee, 1983), (and to the original Millikan White's formulation) this should be done using a different "mixing rule". See also for instance, Eq. (94) in (Zhang et al., 2022). It is even referenced in Eq. (11) of (Maier, et. al 2021) where they employed Mutation++ Is there any particular reason why Gnoffo's approach has been preferred in Mutation's implementation? Is there any chance Gnoffo's equation is wrong? Am I missing something here? Kind regards, Juan Pablo The line where the Millikan White's relaxation time is computed: https://github.com/mutationpp/Mutationpp/blob/master/src/transfer/MillikanWhite.cpp#L144C1-L146C26 Peter A. Gnoffo, Roop N. Gupta, and Judy L. Shinn. Conservation equations and physical models for hypersonic air flows in thermal and chemical nonequilibrium. Technical Paper 2867, NASA, February 1989. J.-H. Lee. Basic Governing Equations for the Flight Regimes of Aeroassisted Orbital Transfer Vehicles. Thermal Design of Aeroassisted Orbital Transfer Vehicles pp. 3-53, AIAA, 1984 https://doi.org/10.2514/6.1984-1729 Maier, W.T.; Needels, J.T.; Garbacz, C.; Morgado, F.; Alonso, J.J.; Fossati, M. SU2-NEMO: An Open-Source Framework for High-Mach Nonequilibrium Multi-Species Flows. Aerospace 2021, 8, 193. https://doi.org/10.3390/aerospace8070193 Zhang, W., Zhang, Z., Wang, X. et al. A review of the mathematical modeling of equilibrium and nonequilibrium hypersonic flows. Adv. Aerodyn. 4, 38 (2022). https://doi.org/10.1186/s42774-022-00125-x |
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Hi Juan Pablo, Thank you for reporting this and for the references attached. The vibrational relaxation time was changed in Mutation++ for consistency with the reference cited. Michele |
Hi Juan Pablo,
Thank you for reporting this and for the references attached.
The vibrational relaxation time was changed in Mutation++ for consistency with the reference cited.
However, I observed that this led to a departure from code-to-code verifications with other codes. I think the best is to allow the user to decide which formulation to use. I will push that soon.
Michele