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Mean Velocity and Shear Stress Distribution in Floating Treatment Wetlands: An Analytical Study

Publication ,  Journal Article
Li, S; Katul, G; Huai, W
Published in: Water Resources Research
August 1, 2019

Floating treatment wetlands (FTWs) are efficient at wastewater treatment; however, data and physical models describing water flow through them remain limited. A two-domain model is proposed dividing the flow region into an upper part characterizing the flow through suspended vegetation and an inner part describing the vegetation-free zone. The suspended vegetation domain is represented as a porous medium characterized by constant permeability thereby allowing Biot's Law to be used to describe the mean velocity and stress profiles. The flow in the inner part is bounded by asymmetric stresses arising from interactions with the suspended vegetated (porous) base and solid channel bed. An asymmetric eddy viscosity model is employed to derive an integral expression for the shear stress and the mean velocity profiles in this inner layer. The solution features an asymmetric shear stress index that reflects two different roughness conditions over the vegetation-induced auxiliary bed and the physical channel bed. A phenomenological model is then presented to explain this index. An expression for the penetration depth into the porous medium defined by 10% of the maximum shear stress is also derived. The predicted shear stress profile, local mean velocity profile, and bulk velocity agree with the limited experiments published in the literature.

Duke Scholars

Published In

Water Resources Research

DOI

EISSN

1944-7973

ISSN

0043-1397

Publication Date

August 1, 2019

Volume

55

Issue

8

Start / End Page

6436 / 6449

Related Subject Headings

  • Environmental Engineering
  • 4011 Environmental engineering
  • 4005 Civil engineering
  • 3707 Hydrology
  • 0907 Environmental Engineering
  • 0905 Civil Engineering
  • 0406 Physical Geography and Environmental Geoscience
 

Citation

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Li, S., Katul, G., & Huai, W. (2019). Mean Velocity and Shear Stress Distribution in Floating Treatment Wetlands: An Analytical Study. Water Resources Research, 55(8), 6436–6449. https://doi.org/10.1029/2019WR025131
Li, S., G. Katul, and W. Huai. “Mean Velocity and Shear Stress Distribution in Floating Treatment Wetlands: An Analytical Study.” Water Resources Research 55, no. 8 (August 1, 2019): 6436–49. https://doi.org/10.1029/2019WR025131.
Li S, Katul G, Huai W. Mean Velocity and Shear Stress Distribution in Floating Treatment Wetlands: An Analytical Study. Water Resources Research. 2019 Aug 1;55(8):6436–49.
Li, S., et al. “Mean Velocity and Shear Stress Distribution in Floating Treatment Wetlands: An Analytical Study.” Water Resources Research, vol. 55, no. 8, Aug. 2019, pp. 6436–49. Scopus, doi:10.1029/2019WR025131.
Li S, Katul G, Huai W. Mean Velocity and Shear Stress Distribution in Floating Treatment Wetlands: An Analytical Study. Water Resources Research. 2019 Aug 1;55(8):6436–6449.
Journal cover image

Published In

Water Resources Research

DOI

EISSN

1944-7973

ISSN

0043-1397

Publication Date

August 1, 2019

Volume

55

Issue

8

Start / End Page

6436 / 6449

Related Subject Headings

  • Environmental Engineering
  • 4011 Environmental engineering
  • 4005 Civil engineering
  • 3707 Hydrology
  • 0907 Environmental Engineering
  • 0905 Civil Engineering
  • 0406 Physical Geography and Environmental Geoscience