Separated flows over swept wings across transitional Reynolds numbers
Abstract
We explore the effect of wing sweep on the interaction between leading-edge separation and tip vortex for a finite wing with sweep angles Λ=0∘ to 45∘, semi-aspect-ratio sAR=2, angle of attack 14∘, and chord-based Reynolds numbers Re=600, $1000$, $2500$, $5000$, and $10000$. Through this parametric study, we seek to bridge the knowledge gap between existing studies on separated flows over swept finite wings at low Reynolds numbers (Re≈ 102) and the behavior of turbulent flows at higher Reynolds numbers (Re≈104). The flow structure significantly varies over this range of parameters, altering the lift characteristics. Specifically, increasing Λ at Re≤5000 reduces the lift, while increasing Λ at Re>5000 enhances the lift. The flow modifications that lead to this effect with increasing Reynolds number are analyzed in terms of the streamwise vorticity, revealing three key effects: (i) a change in the sign of streamwise vorticity with increasing sweep angle, due to the higher spanwise velocity component, (ii) the progressive weakening and eventual disappearance of the tip vortex, when increasing the wing sweep, is accompanied by the emergence of a dominant inboard vortical structure near the root, and (iii) at higher Reynolds numbers and sweep angles, this inboard vortical structure merges with the main wake, intensifying the shear-layer roll-up and giving rise to a leading-edge vortex with an extended reattached region over the wing. These findings reveal how the flow characteristics vary with Reynolds number, transitioning from regimes where swept wings offer limited benefit to regimes where they significantly enhance the aerodynamic performance. This study contributes to a deeper understanding of swept-wing wake dynamics, which is crucial for modern air vehicle design.
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BibTeX
@misc{rolandi2026separated,
title = {{Separated flows over swept wings across transitional Reynolds numbers}},
author = {Laura Victoria Rolandi and Jonathan Quang Tran and Kunihiko Taira},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.38732},
eprint = {2609.38732},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.38732},
}
RIS
TY - UNPB
TI - Separated flows over swept wings across transitional Reynolds numbers
AU - Laura Victoria Rolandi
AU - Jonathan Quang Tran
AU - Kunihiko Taira
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.38732
UR - https://arxiv.org/abs/2609.38732
AB - We explore the effect of wing sweep on the interaction between leading-edge separation and tip vortex for a finite wing with sweep angles Λ=0^∘ to 45^∘, semi-aspect-ratio sAR=2, angle of attack 14^∘, and chord-based Reynolds numbers Re=600, $1000$, $2500$, $5000$, and $10000$. Through this parametric study, we seek to bridge the knowledge gap between existing studies on separated flows over swept finite wings at low Reynolds numbers (Re≈ 10^2) and the behavior of turbulent flows at higher Reynolds numbers (Re≈10^4). The flow structure significantly varies over this range of parameters, altering the lift characteristics. Specifically, increasing Λ at Re≤5000 reduces the lift, while increasing Λ at Re>5000 enhances the lift. The flow modifications that lead to this effect with increasing Reynolds number are analyzed in terms of the streamwise vorticity, revealing three key effects: (i) a change in the sign of streamwise vorticity with increasing sweep angle, due to the higher spanwise velocity component, (ii) the progressive weakening and eventual disappearance of the tip vortex, when increasing the wing sweep, is accompanied by the emergence of a dominant inboard vortical structure near the root, and (iii) at higher Reynolds numbers and sweep angles, this inboard vortical structure merges with the main wake, intensifying the shear-layer roll-up and giving rise to a leading-edge vortex with an extended reattached region over the wing. These findings reveal how the flow characteristics vary with Reynolds number, transitioning from regimes where swept wings offer limited benefit to regimes where they significantly enhance the aerodynamic performance. This study contributes to a deeper understanding of swept-wing wake dynamics, which is crucial for modern air vehicle design.
ER -