When considering the aerodynamic performance of subsonic aircraft, the idea of reducing skin-friction drag is very attractive. Hence, over the past years, several active and passive flow control techniques have been developed to stabilize the boundary-layer flow and delay laminar-to-turbulent transition over its external surface.

Nevertheless, the efficacy of these techniques is limited due to current aircraft design, construction, and maintenance, which creates a non-smooth surface where two-dimensional irregularities in the form of gaps and steps are present. Typically the surface of an aircraft is composed of several panels joined using a lap-splice or a single strap arrangement. Hence, the study of the effect of these two-dimensional surface irregularities on boundary-layer transition is crucial for the implementation of active and passive flow control techniques in the aviation industry.

The application of previous studies to swept wings dominated by Crossflow Instability is limited since they have been mainly conducted in un-swept models, where Tollmien-Schlichting waves instability is dominant. Henceforth this research project focuses on the experimental study of the impact of Forward Facing Steps (FFS) surface irregularities in the stability of a swept-wing boundary-layer flow and the detailed interaction dynamics between the Crossflow Vortices and the FFS.

Rius-Vidales, A. F., & Kotsonis, M. (2021). Impact of a forward-facing step on the development of crossflow instability, Journal of Fluid Mechanics, Vol 924, A34.

Rius-Vidales, A. F., & Kotsonis, M. (2020). Influence of a Forward-Facing Step Surface Irregularity on Swept Wing Transition.AIAA Journal, 58(12), 5243-5253.Rius Vidales, A. F., Kotsonis, M., Antunes, A. P., & Cosin, R. (2018). Effect of two-dimensional surface irregularities on swept wing transition: Forward facing steps.In 2018 AIAA Fluid Dynamics Conference (p. 3075)