Development of an Overset Near-Body Cartesian Solver for Graphite Ablation Simulations

The accurate modeling of hypersonic environments, including coupled ablation, is a challenging problem due to the complex flow physics, numerical accuracy, and robustness required for these simulations. The simulation mesh needs to be designed carefully, and structured high-aspect ratio stretched grids are typically used to properly capture the high wall-normal gradients. The mesh generation process proves to be a cumbersome and time-consuming process for realistic and complex vehicles, creating a severe bottleneck to the current CFD workflow. This work highlights the development of the Cartesian Higher-Order Adaptive Multi-Physics Solver (CHAMPS) near-body Cartesian grid solver, capable of automatic volume mesh generation, and its accurate and robust use in simulating coupled ablation for steady-state graphite ablation by interfacing with the Kentucky Aerothermodynamics and Thermal Response System Material Response (KATS-MR) solver. Validation on a Mach 8.7 cylinder and a Mach 22.88 axisymmetric Mars 2020 capsule showcases the challenges associated with shock-capturing on non-shock-aligned Cartesian grids. A verification study of the CHAMPS–KATS coupled ablation framework is performed for steady-state graphite ablation on a Mach 25.2, 9 deg blunt cone, followed by the validation of the solver for a blunt cone in the NASA Ames Interaction Heating Facility arcjet.