Mean and Turbulent Flow Statistics in a Trellised Agricultural Canopy

Though canopy sublayer turbulence characteristics have been studied extensively, trellised plant canopies, like vineyards, have received relatively little attention and present an en- vironment with similarities to both homogenous plant canopies and urban street canyons. Wind velocity data from a meteorological tower deployed in a vineyard in Oregon demon- strated that the majority of the flow in the canopy was channeled into the vine row direction, regardless of the above-canopy wind direction. The channeling led to measurable turning of the mean velocity profile between the mid-canopy (0.5 canopy heights, h) and the top of the tower (4.7h). When the winds at 4.7h were nearly perpendicular to the vine row direction, profiles of turbulent statistics showed somewhat similar behavior to studies of homogeneous plant canopies. In contrast, when the winds were nearly parallel to the vine row direction, the same statistics were considerably different. The flow characteristics showed a functional dependence on the angular difference between the wind direction and the vine row direc- tion. Large-eddy simulation (LES) and the Quick Urban Industrial Complex mean wind flow model (QUIC-URB) were also used to simulate flow in the vineyard. In both modeling approaches, the canopy architecture is appropriately resolved to match the dimensions from the field. Turbulent and momentum statistics from both were tested as a function of the mean wind direction to test their ability to match the vineyard-determined dependencies. Comparisons between the model and experimental results will be presented.