HR: 16:30h
AN: H54C-03    [Abstracts]
TI: Large Eddy Simulation of Canopy Flows Using Lagrangian Dynamic Model and Comparison with PIV Field Experimental data
AU: * Parlange, M B
EM: marc.parlange@epfl.ch
AF: L'Ecole Polytechnique Federale de Lausanne, School of Architecture, Civil and Environmental Engineering, GR B2 417 Switzerland, Ecublens, 1015 Switzerland
AU: * Parlange, M B
EM: marc.parlange@epfl.ch
AF: Johns Hopkins University, Center for Environmental Fluid Mechanics, 3400 N. Charles St., Baltimore, MD 21218 United States
AU: Yue, W
EM: yue@jhu.edu
AF: Johns Hopkins University, Center for Environmental Fluid Mechanics, 3400 N. Charles St., Baltimore, MD 21218 United States
AU: Meneveau, C
EM: meneveau@jhu.edu
AF: Johns Hopkins University, Center for Environmental Fluid Mechanics, 3400 N. Charles St., Baltimore, MD 21218 United States
AU: Zhu, W
EM: weihong@jhu.edu
AF: Johns Hopkins University, Center for Environmental Fluid Mechanics, 3400 N. Charles St., Baltimore, MD 21218 United States
AU: van Hout, R
EM: renevanhout@jhu.edu
AF: Johns Hopkins University, Center for Environmental Fluid Mechanics, 3400 N. Charles St., Baltimore, MD 21218 United States
AU: Katz, J
EM: katz@jhu.edu
AF: Johns Hopkins University, Center for Environmental Fluid Mechanics, 3400 N. Charles St., Baltimore, MD 21218 United States
AB: The exchange between plants and the atmosphere is one of the main themes in ecohydrology. The realistic simulation of the turbulent flow around plants remains a major challenge. Canopy turbulence is characterized by momentum transfer through aerodynamic drag of foliage throughout the whole depth of the canopy, which leads to an unstable inflected mean velocity profile and enhances dissipation of turbulent kinetic energy by means of wake-scale eddies. We present results on the turbulence structures within and above a canopy at scales appropriate to a corn canopy, using large eddy simulation. The LES employs a dynamic Lagrangian subgrid-scale model. The corn canopy is simulated by two numerical approaches: global-scale and local-scale models. The former treats the canopy as a porous body of horizontally uniform area density. The latter accounts for the specific arrangement of corn plants, taking into account the heterogeneity of the corn canopy from a local-scale view. The computational results are extensively compared with our recent PIV measurements and two previous field experiments by Shaw et al. (1974) and Wilson et al. (1982). The numerical predictions of turbulence statistics and energy spectra are in good agreement with the experimental data. A quadrant analysis shows that sweep events dominate the momentum flux within the canopy while ejection events dominate above the canopy.
DE: 3322 Land/atmosphere interactions
DE: 3379 Turbulence
DE: 3307 Boundary layer processes
DE: 1719 Hydrology
DE: 1851 Plant ecology
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting