On the Influence of Frequency and Spanwise Wavelength on the Formation of Gortler Vortices

The first feature of the laminar-turbulent transition process in boundary layers over concave surfaces is often the emergence of the streamwise-oriented counter-rotating vortices, known as Gortler Vortices. The generation of these vortices occurs due to the imbalance of centrifugal and inertial forces, and the understanding of these vortices is of extreme importance in the industry because it can delay or anticipate the laminar-turbulent transition process. Some recent studies focus on unsteady disturbances to generate steady or unsteady Gortler vortices. This problem is studied here by high-order numerical simulations to verify the evolution and the structure of the steady and unsteady Gortler vortices for different values of spanwise wavelength and disturbance frequencies. The results show that when the spanwise wavelength and time-frequency increase, the flow is not dominated by mode (1, 1) but by (0, 2) and this implies that unsteady disturbances can generate steady Gortler Vortices.