Molecular-level simulations of turbulent Couette flow over a thermal-protection-system material

We report flow statistics and visualizations from molecular-gas-dynamics simulations using the direct simulation Monte Carlo (DSMC) method for turbulent Couette flow in which the lower wall is replaced by a rough and permeable substrate obtained from a three-dimensional image scan of the low-density carbon reinforcement material FiberForm, used to manufacture NASA’s PICA thermal protection material. We focus on near-continuum conditions corresponding to a modest global Reynolds number Re = 2800 and supersonic Mach number Ma = 1.5. Additionally, we present permeability calculations for differing levels of rarefaction and assess the potential for noncontinuum effects on the overlying turbulent flow.