Development and Verification of Nonequilibrium Reacting Airflow Modeling in ANSYS Fluent

High-speed flow problems of practical interest require a solution of nonequilibrium aerothermochemistry to accurately predict important flow phenomena, including surface heat transfer and stresses. The complex coupling of nonequilibrium effects on the aerothermal load remains a challenging aspect of hypersonic flow modeling. As a majority of these flow problems are in the continuum regime, computational fluid dynamics (CFD) is a useful tool for modeling nonequilibrium flows. However, there are a limited number of CFD solvers with nonequilibrium flow modeling capabilities that are highly scalable on parallel architectures and can handle complex geometries. This work demonstrates that a commercial general purpose CFD solver can be effectively modified to include high-fidelity nonequilibrium aerothermochemistry and transport models. The paper presents modifications of a general purpose CFD solver, ANSYS Fluent, using the user defined functions to model salient aspects of nonequilibrium flow in air with a five-species reacting mixture: N₂, O₂, NO, N, and O. The modifications to the solver include Gupta–Yos high temperature mixing laws and Park’s two-temperature nonequilibrium chemistry models. The developed solver was verified for several benchmark nonequilibrium flow problems and compared with the available experimental data and other nonequilibrium flow simulations. The work establishes future possibilities for coupled aerothermal and electromagnetic simulations in thermochemical nonequilibrium.