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Experimental Characterization of the TKE Budget in Flows with Emergent Vegetation

Author(s): Rui M. L. Ferreira; Ana M. Ricardo; Katinkakoll

Linked Author(s): Rui M.L. Ferreira, Ana Margarida Ricardo

Keywords: Turbulence; TKE; LDA; PIV; Vegetation

Abstract: The flow within and above plant canopies in estuarine wetlands is normally turbulent in the inter-stem space. Turbulent kinetic energy (TKE) is mainly produced due to vortex shedding from individual stems. Due to the complex spatial distribution of the flow field, the relative magnitude of the terms of the TKE budget is not well known in the inter-stem space. This work is aimed at the characterization and quantification of the terms of TKE equation to advance the understanding of the nature of turbulence of this kind of flows. The work is fundamentally experimental and is based on the analysis of 3D Laser Doppler Anemometry (LDA) and 2D Particle Image Velocimetry (PIV) databases, for which the spatial resolution is of the order of magnitude of Taylor's microscale. The compatibility of the two databases proved to be sufficiently good. This work leads to the conclusion that turbulent production is mainly wake production. There are important turbulent fluxes of TKE and interactions between the mean and turbulent flow fields. Convective terms are important in the vicinity of the stems while turbulent diffusion is mostly associated to the von Karman vortex streets. The dissipation rate of TKE presents smaller spatial variations and its magnitude increases with the stem areal number-density.


Year: 2013

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