Simulation of hypersonic boundary layer on porous surfaces using OpenFOAM

Hypersonic boundary layer on porous surfaces is numerically investigated using the open-source flow solver OpenFOAM. Computations of hypersonic boundary layer have not been widely conducted especially using open-source flow solvers. The solver rhoEnergyFoam Modesti and Pirozzoli (2017), which has been developed in the OpenFOAM framework, is successfully validated for hypersonic boundary layer flow in the current study. Direct numerical simulations (DNS) of boundary layer at Mach 6 are pursued here with a disturbance related to the Mack second mode. The evolution of the Mack second mode is compared with the current analysis of linear stability theory (LST) and previous DNS data. The stabilization of the Mack second mode on porous surfaces is well resolved in the current computations. In addition to the stabilization of the Mack second mode with porous surfaces, aerothermodynamic features, including drag and surface heat transfer, are investigated. Without porous surfaces, the heat flux variation is even larger than the mean heat flux due to the flow instability. Porous surfaces significantly reduce the heat flux variation to the level of the mean heat flux. Mean drag and heat transfer are marginally affected by porous surfaces. Stress analysis is accompanied to investigate whether the pore structure experiences severe stress under such a high-speed condition. The current investigation on porous surfaces indicates that the surface porosity is an effective method to suppress instabilities and subsequently the heat flux variation on the wall without hampering mean aerothermodynamic characteristics.