A turbulence kinetic energy budget analysis in a windtunnel model canopy

Turbulent flow over a windtunnel model canopy composed of stalks were investigated by large eddy simulation (LES), and the computational results were extensively compared with experimental data from the Particle Image Velocimetry and hotwire measurements. There is an excellent agreement between the LES predictions and the experimental data in turbulence statistics and energy spectra. An inactive `sloshing' motion is found at the low levels of the model canopy. A detailed analysis of turbulent kinetic energy (TKE) budget indicates that the sloshing motion is mainly driven by the pressure transport. The strong turbulence shear production occurs at the top of the stalks. The dissipation rate, mainly contributed from the subgrid scale dissipation, accounts for the largest TKE loss above the model canopy. Inside the model canopy, however, the work against the stalk drag accounts for the largest TKE loss. Deep inside the stalks, all the budget terms are relatively small in magnitudes and the shear production nearly ceases, suggesting that the large-scale turbulent eddies are inhibited by the stalks.