Fidelity management of aerothermodynamic modelling for destructive re-entry

The re-entry process is distinguished by the presence of several fragments with intricate geometries resulting from the demise process, which may lead to complex features in the re-entry flow. An example of these features is shock impingement, which leads to highly localized loading of pressure and heat flux on the bodies' surface. These loads impact the overall dynamics and cannot be captured using state-of-the-art low-fidelity approaches. A multi-fidelity approach is considered to reduce the uncertainty in predictions during a multiple body re-entry. Such an approach allows the usage of low-fidelity models along with high-fidelity methods such as Computational Fluid Dynamics or Direct Simulation Monte Carlo. This research investigates the formulation and use of a strategy for the automatic selection of the level of fidelity in the computation of aerothermodynamic loads acting on bodies undergoing destructive atmospheric re-entry. Based on the Billig formula, which provides an approximation for the definition of a shock-wave envelope for blunt bodies, a criterion to automatically detect when to transition from low-to-high/high-to-low fidelity is proposed. In the present work, the focus will be on the application of a shock-envelope logic to switch between fidelity methods, exploring the influence of the shock waves from leading fragments onto the following fragments.