Hypersonic Vehicle Analyses: The Needs and Challenges of Multidisciplinary Simulations

When considering fluid mechanics and Aerothermodynamics in Hypersonic flight conditions, the timescales involved are much smaller than those associated with material response. The material response is slow while the flow response is fast. To address this, we first fully converge the flow solution through computational fluid dynamics (CFD). We then transfer information from the CFD to the material response code and time resolve the material response. This process continues in a cycle until both the flow and material solutions are fully converged.

This iterative process is automated in our simulations. The meshes used for the solid material (carbon carbon) are unstructured, while a shock-aligned structured mesh is used for the Navier-Stokes equations in the CFD. The CFD and material responses interact along the interface between the two domains. The example shown includes the carbon monoxide mass fraction in the flow field, illustrating the effects of ablation on the vehicle's nose over time.

The changing outer mold line of the vehicle throughout the flight underscores the need for coupling between flow and material responses.