Transport Phenomena in High-speed Wall-bounded Flows Subject to Concave Surface Curvature

Guillermo Araya and Ernie Rivera

Volume 12, Issue 1 (January 2021), pp. 16–23

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  author={Guillermo Araya and Ernie Rivera},
  title={Transport Phenomena in High-speed Wall-bounded Flows Subject to Concave Surface Curvature},
  journal={The Journal of Computational Science Education},
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Turbulent boundary layers that evolve along the flow direction are ubiquitous. Moreover, accounting for the effects of wall-curvature driven pressure gradient and flow compressibility adds significant complexity to the problem. Consequently, hypersonic spatially-developing turbulent boundary layers (SDTBL) over curved walls are of crucial importance in aerospace applications, such as unmanned high-speed vehicles, scramjets, and advanced space aircraft. More importantly, hypersonic capabilities would provide faster responsiveness and longer range coverage to U.S. Air Force systems. Thus, the acquired understanding of the physics behind high speed boundary layers over curved wall-bounded flows can lead to the development of more efficient control techniques for the fluid flow (e.g., wave drag reduction) and aerodynamic heating on hypersonic vehicle design. In this investigation, a series of numerical experiments is performed to evaluate the effects of strong concave curvature and supersonic/hypersonic speeds (Mach numbers of 2.86 and 5, respectively) on the thermal transport phenomena that take place inside the boundary layer. The flow solver to be used is based on a RANS approach. Two different turbulence models are compared: the SST (Shear Stress Transport) model by Menter and the standard k-ω model by Wilcox. Furthermore, numerical results are validated by means of experimental data from the literature (Donovan et al., J. Fluid Mech., 259, 1-24, 1994) for the moderate concave curvature case and a Mach number of 2.86. The present study allows us to initially obtain a first insight of the flow physics for a forthcoming better design of 3D meshes and computational boxes, as part of a more ambitious project that involves Direct Numerical Simulation (DNS) of curved wall-bounded flows in the supersonic/hypersonic regime. The uniqueness of this RANS analysis in concave curved walls can be summarized as follows: (i) study of the compressibility effects on the time-averaged velocity and temperature, (ii) analysis of the influence of different inflow boundary conditions.