The efficacy of immersed boundary (IB) methods with adaptive mesh refinement (AMR) techniques is assessed in the context of atmospheric entry applications, including effects of chemical nonequilibrium (CNE) and gas–surface interactions (GSI). We scrutinize a conservative cut-cell IB method and two non-conservative IB methods, comparing their results with analytical solutions, data from the literature, and results obtained with a reference solver that operates on body-fitted grids. All solvers employ the same external thermochemistry library, ensuring that all observed differences can be attributed solely to differences in the underlying numerical methodologies. We present results for eight benchmark cases. Four verification cases verify the implementation of chemistry, transport properties, catalytic boundary conditions, and shock capturing. Four validation cases encompass blunt geometries with adiabatic and isothermal, as well as inert, catalytic and ablative boundary conditions. Overall, the results obtained with the IB solvers are in very good agreement with the reference data. Discrepancies arise in cases with large temperature or concentration gradients at the wall, and these are linked to conservation errors inherent to ghost-cell and interpolation-based IB methods. Only a strictly conservative cut-cell IB method is on par with body-fitted grid methods. ... Read more

During atmospheric entry, the flow environment around capsules or space debris is characterized by complex fluid thermochemistry and gas-surface interactions (GSI). Computational fluid dynamics (CFD) simulations of these conditions are crucial in the design process of such objects. A promising approach for the simulation of complex geometries is the use of immersed boundary methods (IBM) and adaptive mesh refinement techniques (AMR). These methods offer reliable and efficient mesh generation and adaptation with minimal user intervention. To that end, this paper presents the recent developments of two IBM-AMR solvers coupled with the same external thermochemistry library for the accurate modelling of such complex flows including GSI. Several verification and validation cases are presented, which demonstrate the performance of the solvers. Results are analyzed in comparison with a body-conforming solver that uses the same thermochemistry library to achieve a consistent assessment of the underlying numerical methods. A good agreement between all the solvers is indicated with certain discrepancies arising due to the differences in surface treatments. ... Read more