On the Modelling of High Speed Turbulent Flows with Applications towards Reentry Ablation

The fluid dynamics of an ablating hypersonic turbulent boundary layer is a complex process with strong coupling to the surface response. The overarching objective of our research is to improve the accuracy of turbulent heat flux and shear stress modeling for this class of flow. Our approach is to first establish physics based transport equation frameworks for model development, and then perform model driven experiments to isolate underlying phenomena. Among the complications is roughness and streamline curvature induced mechanical non- equilibrium. In this presentation, a description of a recent Mach 5 experimental campaign focused on characterizing the role of these complications on the Reynolds stresses is given first. This is followed by a discussion of the impact on modeling and control. The results from the study are encouraging from the perspectives that (1) existing Reynolds stress transport and large-eddy methods show promise in capturing the observed processes provided suitable understanding of the turbulence structure is achieved and (2) the mechanisms appear controllable