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Thermally Driven Exchange Flow Between Open Water and Floating Vegetation

Sharifi, Elham | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45595 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Jamali, Mirmosadegh
  7. Abstract:
  8. In this thesis, we present the results of a laboratory and numerical model study of the exchange flow generated by the temperature gradient between an open water heated by sunlight and a canopy area made of floating vegetation. Particle Image Velocimetry is employed to obtain the structures of the warm flow intruding the canopy at the surface and the bottom cold return flow for different roots length and vegetation density. Following an initial, transient stage of flow build-up governed by a balance between inertia and buoyancy forces, the flow reaches a steady state in the canopy area with a force balance between buoyancy and vegetation drag dominating the flow within roots. At the steady state, the flow underneath the roots is governed by balance between buoyancy and fluid viscous forces. Depending on the relative magnitude of the root length and the light penetration depth, four regimes of flow were detected. In particular, when the roots are short relative to the light penetration depth, the intrusion flow displaces under the roots layer whereas when the roots are long enough, the intrusion is fully contained in the roots layer and the return flow is confined to a near-bed region with an almost stagnant layer flowing between the two. The experiments confirm the results of the scaling analysis as well as numerical modeling
  9. Keywords:
  10. Exchange Flow ; Particle Image Velocimetery (PIV) ; Solar Heating ; Image Processing ; Floating Vegetation

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