Numerical simulation of a rough-wall pipe from the transitionally rough regime to the fully rough regime

Leon Zen Hsien Chan, M. MacDonald, D. Chung, N. Hutchins, A. Ooi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Turbulent flow of a rough-wall pipe is simulated using Direct Numerical Simulations (DNS) at low and medium Reynolds number from the transitionally rough regime to the fully rough regime. The rough surfaces simulated consist of three-dimensional sinusoidal roughness elements. The size of the roughness (roughness semi-amplitude height h+ and wavelength λ+) is increased geometrically while maintaining the height-to-wavelength ratio of the sinusoidal roughness element. A method is developed to accurately calculate the roughness function ΔU+ for the simulations conducted at low Reynolds number. For this surface, the flow is fully rough when h+ ≈ 60 (simulated at Reτ = 540). This corresponds to k+s ≈ 4.1h+ where k+s is Nikuradse's equivalent sandgrain roughness. A linear trend is observed when the ratio of the apparent wall shear stress due to form drag on the roughness elements to the total wall shear stress Rτ = τR/τT is plotted against the log of the roughness height h+. This linear trend is also observed in the transitionally rough regime. For all the rough-wall pipe simulations conducted, Townsend's [15] outer layer similarity hypothesis holds true.

Original languageEnglish
Title of host publicationProceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014
PublisherAustralasian Fluid Mechanics Society
ISBN (Electronic)9780646596952
Publication statusPublished - 01 Jan 2014
Event19th Australasian Fluid Mechanics Conference, AFMC 2014 - Melbourne, Australia
Duration: 08 Dec 201411 Dec 2014

Publication series

NameProceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014

Other

Other19th Australasian Fluid Mechanics Conference, AFMC 2014
CountryAustralia
CityMelbourne
Period08/12/1411/12/14

Fingerprint

Surface roughness
Pipe
Computer simulation
Shear stress
Reynolds number
Wavelength
Direct numerical simulation
Turbulent flow
Drag

All Science Journal Classification (ASJC) codes

  • Fluid Flow and Transfer Processes

Cite this

Chan, L. Z. H., MacDonald, M., Chung, D., Hutchins, N., & Ooi, A. (2014). Numerical simulation of a rough-wall pipe from the transitionally rough regime to the fully rough regime. In Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014 (Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014). Australasian Fluid Mechanics Society.
Chan, Leon Zen Hsien ; MacDonald, M. ; Chung, D. ; Hutchins, N. ; Ooi, A. / Numerical simulation of a rough-wall pipe from the transitionally rough regime to the fully rough regime. Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014. Australasian Fluid Mechanics Society, 2014. (Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014).
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abstract = "Turbulent flow of a rough-wall pipe is simulated using Direct Numerical Simulations (DNS) at low and medium Reynolds number from the transitionally rough regime to the fully rough regime. The rough surfaces simulated consist of three-dimensional sinusoidal roughness elements. The size of the roughness (roughness semi-amplitude height h+ and wavelength λ+) is increased geometrically while maintaining the height-to-wavelength ratio of the sinusoidal roughness element. A method is developed to accurately calculate the roughness function ΔU+ for the simulations conducted at low Reynolds number. For this surface, the flow is fully rough when h+ ≈ 60 (simulated at Reτ = 540). This corresponds to k+s ≈ 4.1h+ where k+s is Nikuradse's equivalent sandgrain roughness. A linear trend is observed when the ratio of the apparent wall shear stress due to form drag on the roughness elements to the total wall shear stress Rτ = τR/τT is plotted against the log of the roughness height h+. This linear trend is also observed in the transitionally rough regime. For all the rough-wall pipe simulations conducted, Townsend's [15] outer layer similarity hypothesis holds true.",
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Chan, LZH, MacDonald, M, Chung, D, Hutchins, N & Ooi, A 2014, Numerical simulation of a rough-wall pipe from the transitionally rough regime to the fully rough regime. in Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014. Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014, Australasian Fluid Mechanics Society, 19th Australasian Fluid Mechanics Conference, AFMC 2014, Melbourne, Australia, 08/12/14.

Numerical simulation of a rough-wall pipe from the transitionally rough regime to the fully rough regime. / Chan, Leon Zen Hsien; MacDonald, M.; Chung, D.; Hutchins, N.; Ooi, A.

Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014. Australasian Fluid Mechanics Society, 2014. (Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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AB - Turbulent flow of a rough-wall pipe is simulated using Direct Numerical Simulations (DNS) at low and medium Reynolds number from the transitionally rough regime to the fully rough regime. The rough surfaces simulated consist of three-dimensional sinusoidal roughness elements. The size of the roughness (roughness semi-amplitude height h+ and wavelength λ+) is increased geometrically while maintaining the height-to-wavelength ratio of the sinusoidal roughness element. A method is developed to accurately calculate the roughness function ΔU+ for the simulations conducted at low Reynolds number. For this surface, the flow is fully rough when h+ ≈ 60 (simulated at Reτ = 540). This corresponds to k+s ≈ 4.1h+ where k+s is Nikuradse's equivalent sandgrain roughness. A linear trend is observed when the ratio of the apparent wall shear stress due to form drag on the roughness elements to the total wall shear stress Rτ = τR/τT is plotted against the log of the roughness height h+. This linear trend is also observed in the transitionally rough regime. For all the rough-wall pipe simulations conducted, Townsend's [15] outer layer similarity hypothesis holds true.

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Chan LZH, MacDonald M, Chung D, Hutchins N, Ooi A. Numerical simulation of a rough-wall pipe from the transitionally rough regime to the fully rough regime. In Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014. Australasian Fluid Mechanics Society. 2014. (Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014).