Title page for ETD etd-09152008-092311

Type of Document Master's Thesis
Author Liu, David
URN etd-09152008-092311
Title Flow through Rigid Vegetation Hydrodynamics
Degree Master of Science
Department Civil Engineering
Advisory Committee
Advisor Name Title
Diplas, Panayiotis Committee Chair
Gutierrez, Marte S. Committee Member
Hession, W. Cully Committee Member
  • Submerged Vegetation
  • Two Layer Vegetation
  • Emergent Vegetation
  • Velocity Profile Inflection Point
  • Turbulence Intensity
  • Mixing Layer
Date of Defense 2008-09-12
Availability unrestricted
Better understanding of the role of vegetation in the transport of fluid and pollutants requires improved knowledge of the detailed flow structure within the vegetation. Instead of spatial averaging, this study uses discrete measurements at multiple locations within the canopy to develop velocity and turbulence intensity profiles and observe the changes in the flow characteristics as water travels through a vegetation array simulated by rigid dowels. Velocity data were collected with a one dimensional laser Doppler velocimeter (LDV) under single layer emergent and submerged flow conditions, and through two layers of vegetation. The effects of dowel arrangement, density, and roughness are also examined under the single layer experiments. The results show that the velocity within the vegetation array is constant with depth and the velocity profile is logarithmic above it. The region immediately behind a dowel, where the vorticity and turbulence intensity are highest, is characterized by a velocity spike near the bed and an inflection point near the top of the dowel arrays. With two dowel layers, the velocity profile in the region behind a tall dowel exhibits multiple inflection points and the highest turbulence intensities are found there.
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