The stabilizing effect of grooves on Gortler instability-induced boundary layer transition in hypersonic flow

Gortler vortex-induced hypersonic boundary layer transition controlled by grooves is investigated using direct numerical simulations and spatial bi-global stability analysis. In the simulations, Gortler vortices are excited by wall steady blowing and suction with spanwise wavelengths of 3 mm. It is found that when the wall is covered with grooves, the Gortler streaks keep more regular even at the end of the model. In addition, the skin friction coefficient is reduced efficiently. Furthermore, the wall-normal and spanwise velocity shear are both reduced, suppressing growths of secondary instabilities. In conclusion, grooves can delay Gortler vortex-induced transition by modifying the Gortler streaks structure and instability, which would shed light on hypersonic boundary layer transition control.

Automated summary

The study investigates Gortler vortex-induced hypersonic boundary layer transition controlled by grooves using direct numerical simulations and spatial bi-global stability analysis. The simulations show that the presence of grooves on the wall leads to more regular Gortler streaks, even at the end of the model. Furthermore, the grooves reduce the skin friction coefficient and the wall-normal and spanwise velocity shear, which suppress the growth of secondary instabilities. In conclusion, grooves can delay Gortler vortex-induced transition by modifying the Gortler streaks structure and instability, providing insights into hypersonic boundary layer transition control.