Description: Design of reentry vehicles is driven by aeroheating concerns at elevated flow enthalpies. Therefore, accurate simulation of hypersonic flow phenomena such as detached bow shocks is of critical importance to reduce conservatism in design and unlock improved performance. Adaptive mesh refinement (AMR) is an enabling technology to efficiently reduce numerical error in hypersonic reacting flow simulations by providing mesh resolution only where it is needed, based on flow phenomena or an engineering quantity of interest. During Phase I, in collaboration with Mississippi State University, ATA has developed a novel toolset for metric-aligned Hypersonic Anisotropic Adaptive Mesh Refinement (HAAMR). HAAMR was implemented in Loci/CHEM, an ITAR-restricted reacting flow CFD solver developed by MSU and made freely available to NASA, DoD, and their contractors. HAAMR showed similar results to NASAs Data Parallel Line Relaxation (DPLR) structured mesh CFD solver, for 2D non-reacting flow Earth reentry verification cases. The Phase II effort will focus on extending HAAMR capabilities to 3D meshes, as well as improving results when coupling HAAMR with additional physics models that are already present in Loci/CHEM, such as reacting flows and walls, thermodynamic nonequilibrium, and ionized flows. The proposed Phase II innovations twill result in comparable flow physics modeling capabilities to DPLR; however, the unstructured mesh methods of HAAMR and Loci/CHEM will enable efficient simulation of more complex 3D geometries. When coupled with ongoing and upcoming adjacent ATA research efforts, including implementation of shock layer radiation coupling, innovations in kinetic mechanism reduction for reacting and combusting flows, and creation of efficiently trained multi-fidelity machine learning (ML) aerothermal surrogate models, Loci/CHEM will present a leading-edge CFD solution that will directly address identified needs for innovations in simulating reentry and hypersonic flows

Benefits: In fielding a new class of launch, and reentry vehicles, particularly on programs such as Artemis, NASA will rely on simulation-based qualification of new designs, a paradigm that places extreme demands on CFD solvers, in particular, to populate comprehensive aerodynamic databases from full-vehicle, full-trajectory simulations involving evolving vehicle geometry. Even with the vast HPC resources available, HAAMR will be a critical enabling technology to reduce risk and ensure mission range and survivability of these next-generation systems.