Modelling transitional rough-wall turbulence with quasi-linear approximations
File(s)
Accepted version
Author(s)
Jiao, Yuxin
Zou, Zecheng
Bagheri, Shervin
Hwang, Yongyun
Type
Journal Article
Abstract
The effects of surface roughness in the transitionally rough regime on the overlying near-wall turbulence are modelled using quasi-linear approximations proposed recently: minimal quasi-linear approximation (MQLA) (Hwang & Ekchardt, 2020, J. Fluid Mech., vol. 894, A23), data-driven quasi-linear approximation (DQLA) (Holford et al., 2024, J. Fluid Mech., vol. 980, A12) and a newly established variant of MQLA (M2QLA, minimal two-mode quasi-linear approximation). The transpiration-resistance model (TRM) for boundary conditions is applied to account for the surface roughness (Lācis et al., 2020, J. Fluid Mech., vol. 884, A21). It is shown that many essential near-wall turbulence statistics are fairly well captured by the quasi-linear approximations in a wide range of slip and transpiration lengths for the TRM boundary conditions. In particular, the virtual origins and the resulting roughness functions are well predicted, showing good agreement with those from previous direct numerical simulations (DNS) in mild roughness cases. The DQLA and M2QLA, which incorporate streamwise-dependent Fourier modes in the approximations, are also shown to perform a little better than MQLA, especially with DQLA reproducing the two-dimensional energy spectra qualitatively consistent with the DNS. Finally, with a computational cost much lower than DNS, it is shown that the proposed quasi-linear approximation frameworks offer an efficient tool to rapidly explore the roughness effects within a large parameter space.
Date Issued
2025-08-10
Date Acceptance
2025-06-12
Citation
Journal of Fluid Mechanics, 2025, 1016
ISSN
0022-1120
Publisher
Cambridge University Press
Journal / Book Title
Journal of Fluid Mechanics
Volume
1016
Copyright Statement
Copyright © The Author(s), 2025. Published by Cambridge University Press. This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Subjects
ATTACHED EDDIES
CHANNEL FLOW
DIRECT NUMERICAL-SIMULATION
DRAG REDUCTION
ENERGY AMPLIFICATION
LARGE-SCALE STRUCTURES
low-dimensional models
Mechanics
OPPOSITION CONTROL
Physical Sciences
Physics
Physics, Fluids & Plasmas
Science & Technology
SLIP
SURFACE
Technology
TRANSVERSE
turbulence control
turbulence modelling
Publication Status
Published
Article Number
A7
Date Publish Online
2025-07-29