Reynolds number effects on surface-induced secondary flows in turbulent boundary layers
Fuente:
arXiv
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| Autori principali: | , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866908288280428544 |
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| author | Medjnoun, T. Nillson-Takeuchi, M. Ganapathisubramani, B. |
| author_facet | Medjnoun, T. Nillson-Takeuchi, M. Ganapathisubramani, B. |
| contents | This study explores the effect of friction Reynolds number ($Re_τ\approx 3{,}000$--$13{,}000$) on secondary flows in three-dimensional turbulent boundary layers induced by spanwise surface heterogeneity. Using a combination of floating-element drag balance and high-resolution hot-wire anemometry, we examine how varying spanwise spacing ($S/δ$) influences frictional drag, turbulence intensity, spectral energy distribution, and the organisation of coherent structures. The results reveal that secondary flows modulate turbulence differently depending on $S/δ$, with strong near-wall effects at $S/δ< 1$ and outer-layer modulation at $S/δ\gtrsim 1$. A robust spectral signature of secondary flows peaking at $λ_x \approx 3δ$ and $y \approx 0.5δ$ emerges across all cases. This peak coexists with, or suppresses, very-large-scale motions (VLSMs), depending on flow region and spacing. While VLSMs are suppressed in low-momentum pathways (LMPs), they gradually recover in high-momentum pathways (HMPs) at higher $S/δ$ and $Re_τ$. These findings offer new insight into the interplay between secondary motions and scale interactions in three-dimensional turbulent boundary layers, with implications for drag control, mixing, and surface design. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_22029 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Reynolds number effects on surface-induced secondary flows in turbulent boundary layers Medjnoun, T. Nillson-Takeuchi, M. Ganapathisubramani, B. Fluid Dynamics This study explores the effect of friction Reynolds number ($Re_τ\approx 3{,}000$--$13{,}000$) on secondary flows in three-dimensional turbulent boundary layers induced by spanwise surface heterogeneity. Using a combination of floating-element drag balance and high-resolution hot-wire anemometry, we examine how varying spanwise spacing ($S/δ$) influences frictional drag, turbulence intensity, spectral energy distribution, and the organisation of coherent structures. The results reveal that secondary flows modulate turbulence differently depending on $S/δ$, with strong near-wall effects at $S/δ< 1$ and outer-layer modulation at $S/δ\gtrsim 1$. A robust spectral signature of secondary flows peaking at $λ_x \approx 3δ$ and $y \approx 0.5δ$ emerges across all cases. This peak coexists with, or suppresses, very-large-scale motions (VLSMs), depending on flow region and spacing. While VLSMs are suppressed in low-momentum pathways (LMPs), they gradually recover in high-momentum pathways (HMPs) at higher $S/δ$ and $Re_τ$. These findings offer new insight into the interplay between secondary motions and scale interactions in three-dimensional turbulent boundary layers, with implications for drag control, mixing, and surface design. |
| title | Reynolds number effects on surface-induced secondary flows in turbulent boundary layers |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2503.22029 |