Stabilization of a Swept-Wing Boundary Layer by Discrete Roughness Elements at High Reynolds Numbers


Direct numerical simulations (DNS) are performed to study potential stabilizing effect of spanwise periodic discrete roughness elements (DREs) on crossflow instabilities in a spatially developing three-dimensional boundary layer over an infinite-swept natural-laminar-flow wing at a freestream Mach number of 0.75 and a chord Reynolds number of approximately 25 million. In the DNS, both the spanwise periodic DREs and distributed roughness in the leading-edge region are implemented to simulate a typical experimental scenario in which multiple steady crossflow modes including the most unstable mode (i.e., the "target" mode) emerge because of the presence of naturally distributed surface roughness in the leading edge region and spanwise periodic control cylinders of subcritical wavelength are used to force small-wavelength disturbances (i.e., the control mode) for damping the target mode. The DNS results show that the effectiveness of DRE control is sensitive to roughness diameter, height, and chordwise placement. For the DRE parameters considered in this study, the stabilizing effect on the target mode is small within the computational domain that ended at about 35% of the chord.

Meeting Name

AIAA Scitech Forum, 2019 (2019: Jan. 7-11, San Diego, CA)


Mechanical and Aerospace Engineering


This work was originally sponsored under the NASA Environmentally Responsible Aviation Project.

Keywords and Phrases

Aviation; Laminar flow; Reynolds number; Surface roughness; Swept wings, Computational domains; Cross-flow instabilities; Freestream mach number; High Reynolds number; Natural laminar flows; Stabilizing effects; Swept-wing boundary layers; Three-dimensional boundary layers, Laminar boundary layer

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Article - Conference proceedings

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© 2019 American Institute of Aeronautics and Astronautics (AIAA), All rights reserved.

Publication Date

01 Jan 2019