Effect of two-dimensional surface irregularities on swept wing transition: Forward facing steps

Alberto F. Rius Vidales*, Marios Kotsonis, Alexandre Antunes, Renato Cosin

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

10 Citations (Scopus)
60 Downloads (Pure)


An experimental investigation was carried out to examine the effect of two-dimensional Forward Facing Steps surface irregularities, on the laminar-to-turbulent boundary-layer transition on a 45° swept-wing. For the clean reference case, the numerical boundary-layer flow is calculated from pressure measurements, and a thorough linear stability analysis is performed for all variations of Reynolds number and angle of attack. Infrared thermography is employed to determine the transition-front location which is associated to an N-Factor, calculated from the linear stability analysis. The change in the amplification factor ∆N, caused by the addition of the surface irregularity, is analyzed. The reduction in the critical N-factor is observed to correlate with the estimated cross-flow instability vortex core height to step height ratio and the relative step height. The work presented in this paper is part of an ongoing research project to characterize the effect that surface irregularities have on boundary layer transition. The N-method offers an overview of the phenomena related to FFS, capable of guiding future investigations into the underlying flow mechanisms.

Original languageEnglish
Title of host publication2018 Fluid Dynamics Conference
PublisherAmerican Institute of Aeronautics and Astronautics Inc. (AIAA)
Number of pages16
ISBN (Electronic)9781624105531
Publication statusPublished - 1 Jan 2018
Event48th AIAA Fluid Dynamics Conference, 2018 - Atlanta, United States
Duration: 25 Jun 201829 Jun 2018


Conference48th AIAA Fluid Dynamics Conference, 2018
Country/TerritoryUnited States

Bibliographical note

Correction Notice
• In section V. Conclusions, the third sentence of the third paragraph should read: “A critical regime in which there was a noticeable change in the transition front pattern, and the transition location rapidly shifted upstream towards the step location, departing in this way from the trend indicated by the clean baseline.”


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