Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/144150
Title: Coherent structures over riblets in turbulent boundary layer studied by combining time-resolved particle image velocimetry (TRPIV), proper orthogonal decomposition (POD), and finite-time Lyapunov exponent (FTLE)
Authors: Li, Shan
Jiang, Nan
Yang, Shaoqiong
Huang, Yongxiang
Wu, Yanhua
Keywords: Engineering::Aeronautical engineering
Issue Date: 2018
Source: Li, S., Jiang, N., Yang, S., Huang, Y, & Wu Y. (2018). Coherent structures over riblets in turbulent boundary layer studied by combining time-resolved particle image velocimetry (TRPIV), proper orthogonal decomposition (POD), and finite-time Lyapunov exponent (FTLE)*. Chinese Physics B, 27(10), 104701-. doi:10.1088/1674-1056/27/10/104701
Journal: Chinese Physics B
Abstract: Time-resolved particle image velocimetry (TRPIV) experiments are performed to investigate the coherent structure's performance of riblets in a turbulent boundary layer (TBL) at a friction Reynolds number of 185. To visualize the energetic large-scale coherent structures (CSs) over a smooth surface and riblets, the proper orthogonal decomposition (POD) and finite-time Lyapunov exponent (FTLE) are used to identify the CSs in the TBL. Spatial-temporal correlation is implemented to obtain the characters and transport properties of typical CSs in the FTLE fields. The results demonstrate that the generic flow structures, such as hairpin-like vortices, are also observed in the boundary layer flow over the riblets, consistent with its smooth counterpart. Low-order POD modes are more sensitive to the riblets in comparison with the high-order ones, and the wall-normal movement of the most energy-containing structures are suppressed over riblets. The spatial correlation analysis of the FTLE fields indicates that the evolution process of the hairpin vortex over riblets are inhibited. An apparent decrease of the convection velocity over riblets is noted, which is believed to reduce the ejection/sweep motions associated with high shear stress from the viscous sublayer. These reductions exhibit inhibition of momentum transfer among the structures near the wall in the TBL flows.
URI: https://hdl.handle.net/10356/144150
ISSN: 1674-1056
DOI: 10.1088/1674-1056/27/10/104701
Rights: © 2018 Chinese Physical Society and IOP Publishing Ltd. All rights reserved.
Fulltext Permission: none
Fulltext Availability: No Fulltext
Appears in Collections:MAE Journal Articles

Google ScholarTM

Check

Altmetric


Plumx

Items in DR-NTU are protected by copyright, with all rights reserved, unless otherwise indicated.