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Three-Dimensional Velocity Distribution in Straight Smooth Channels Modeled by Modified Log-Law

Journal Article


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Abstract


  • Time-average velocity distribution in steady and uniform channel flows is important for fundamental research and practical application as it is always three-dimensional (3D), regardless of channel geometry. However, its determination has predominantly been carried out by using complex numerical software, even for the simplest geometry such as rectangular channels. The log-law was developed initially for circular pipe flows, where a single shear velocity is used to normalize the velocity (u+) and its distance (y+). Tracy and Lester found that the performance of the log-law can be extended to express velocity profiles in rectangular channels when the global shear velocities (gRS)0.5 and (ghS)0.5 are used to normalize the measured velocity u and its distance y. This study extends this discovery from the channel central line to the corner regions, and its general form of log-law was found to be valid even in trapezoidal or triangular open channels or closed ducts. This modified log-law can produce good agreement with the measured velocity with an average error of less than 5%. Therefore, this study provides a simple and reliable tool for engineers and researchers to estimate the velocity contours in straight and smooth channel flows.

Publication Date


  • 2020

Citation


  • Yang, S., Riaz, M., Sivakumar, M., Enever, K. & Miguntanna, N. Sajeewani. (2020). Three-Dimensional Velocity Distribution in Straight Smooth Channels Modeled by Modified Log-Law. Journal of Fluids Engineering, 142 (1), 011401-1-011401-8.

Ro Full-text Url


  • https://ro.uow.edu.au/context/eispapers1/article/4780/type/native/viewcontent

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers1/3754

Start Page


  • 011401-1

End Page


  • 011401-8

Volume


  • 142

Issue


  • 1

Place Of Publication


  • United States

Abstract


  • Time-average velocity distribution in steady and uniform channel flows is important for fundamental research and practical application as it is always three-dimensional (3D), regardless of channel geometry. However, its determination has predominantly been carried out by using complex numerical software, even for the simplest geometry such as rectangular channels. The log-law was developed initially for circular pipe flows, where a single shear velocity is used to normalize the velocity (u+) and its distance (y+). Tracy and Lester found that the performance of the log-law can be extended to express velocity profiles in rectangular channels when the global shear velocities (gRS)0.5 and (ghS)0.5 are used to normalize the measured velocity u and its distance y. This study extends this discovery from the channel central line to the corner regions, and its general form of log-law was found to be valid even in trapezoidal or triangular open channels or closed ducts. This modified log-law can produce good agreement with the measured velocity with an average error of less than 5%. Therefore, this study provides a simple and reliable tool for engineers and researchers to estimate the velocity contours in straight and smooth channel flows.

Publication Date


  • 2020

Citation


  • Yang, S., Riaz, M., Sivakumar, M., Enever, K. & Miguntanna, N. Sajeewani. (2020). Three-Dimensional Velocity Distribution in Straight Smooth Channels Modeled by Modified Log-Law. Journal of Fluids Engineering, 142 (1), 011401-1-011401-8.

Ro Full-text Url


  • https://ro.uow.edu.au/context/eispapers1/article/4780/type/native/viewcontent

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers1/3754

Start Page


  • 011401-1

End Page


  • 011401-8

Volume


  • 142

Issue


  • 1

Place Of Publication


  • United States