Turbulent kinetic energy budgets in a model canopy: comparisons between LES and wind-tunnel experiments |
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| Authors: | Wusi Yue Charles Meneveau Marc B Parlange Weihong Zhu Hyung Suk Kang Joseph Katz |
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| Institution: | (1) Department of Geography and Environmental Engineering, and Center for Environmental and Applied Fluid Mechanics, The Johns Hopkins University, Baltimore, MD 21218, USA;(2) Department of Mechanical Engineering, and Center for Environmental and Applied Fluid Mechanics, The Johns Hopkins University, Baltimore, MD 21218, USA;(3) School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Federale de Lausanne, Lausanne, CH, 1015, Switzerland |
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| Abstract: | A comparative study of turbulence in a wind-tunnel model canopy is performed, using Large eddy simulation (LES) and experimental
data from PIV and hot-wire anemometry measurements. The model canopy is composed of thin cylindrical stalks. In the LES, these
are represented using a plant-scale approach, while the scale-dependent Lagrangian dynamic model is used as subgrid-scale
model. LES predictions of turbulence statistics and energy spectra are found to be in good agreement with the experimental
data. Turbulent kinetic energy (TKE) budgets from the LES simulation are analyzed to provide more information absent in the
measurements. Results confirm that sloshing motions at the low levels of the canopy are mainly driven by pressure fluctuations.
A difference between the energy flux obtained from the energy spectrum and the SGS dissipation rate is observed, consistent
with a spectral bypass mechanism in which the real spectral flux due to cascade is smaller than that implied by the energy-spectrum
level, due to direct drain by the canopy. |
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| Keywords: | Wind-tunnel model canopy Large eddy simulation Energy spectrum Turbulent kinetic energy budget Particle image velocimetry Hotwire anemometer |
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