Duan, G. and Gao, R. and Zhao, L. and Yang, T. and Ngan, K. (2024) Turbulent flow over aligned cylindrical obstacles. Physics of Fluids, 36 (7). 075114. ISSN 1070-6631, DOI https://doi.org/10.1063/5.0211112.
Full text not available from this repository.Abstract
Turbulent flow and boundary-layer (BL) characteristics over cylindrical obstacles have been understudied compared to the flow dynamics around cubic roughness in the urban BL literature. Using large-eddy simulation, we investigate a turbulent BL flow developed over two vertically oriented cylindrical obstacles aligned downstream. For widely separated cylinders, the wake flow undergoes periodic oscillations akin to vortex shedding behind an isolated cylinder. As the height-to-width aspect ratio (AR) of the canyon bounded by the cylinders increases, the streamline geometry exhibits a clear transition from isolated to wake interference and skimming regimes. Two-point autocorrelation functions of velocities confirm a strong coupling of canyon flow with the roughness sublayer for wider canyons, while with evident decoupling as the canyon narrows. The length scales, which measure the spatial correlation in the flow, decrease in both lateral and vertical directions with increasing AR. Turbulent kinetic energy and momentum fluxes below the roughness sublayer present pronounced monotonic scaling with AR (with R-squared values up to 0.84 and 0.98, respectively), resulting in a consistent variation in the surface roughness aerodynamic parameters, the roughness length (z0) and zero-plane displacement (d), with AR. Quantitative differences in the results with respect to those well-established for street canyons are analyzed, with the similarities highlighted. The results offer insights into boundary-layer flow parameterization concerning cylinder-occupied surface roughness.
| Item Type: | Article |
|---|---|
| Funders: | Hong Kong Research Grants Council (CityU 11308021), Natural Science Foundation of Liaoning Province (2022-KF-18-07), National Key Research & Development Program of China (2020YFC1909305) |
| Subjects: | Q Science > Q Science (General) |
| Divisions: | Deputy Vice Chancellor (Research & Innovation) Office > Institute of Ocean and Earth Sciences |
| Depositing User: | Ms. Juhaida Abd Rahim |
| Date Deposited: | 25 Mar 2025 02:38 |
| Last Modified: | 25 Mar 2025 02:38 |
| URI: | http://eprints.um.edu.my/id/eprint/46845 |
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