Large-Eddy Simulations of Inhomogeneous Canopy Flows
The investigation of the turbulent flow within and above canopies is the key to understand the exchange processes between the atmosphere and vegetation. These processes influence the microclimate of plant growing and the atmospheric boundary layer (ABL). Reflecting the effects of forest edges, clearings and other inhomogeneities on the ABL lead to a better understanding of the propagation of tracer gases and the improvement of flux measurement methods. Within a Large-Eddy-Simulation (LES), these strong anisotropic turbulence effects generated by the vegetation have to be considered by subgrid-scale (SGS) models. The model used by the authors is a single equation transport model presented by Shaw and Schumann, [2] and still state-of-the-art. The vegetation is represented by a leaf area density (LAD) profile, which is often based only on spatially limited measurements and often only varies with height. The LAD distribution used for the presented simulations is obtained by terrestrial laser scanning methods and therefore of very high resultion for the whole solution domain of 192 m x 96 m x 120 m. The results are compared to wind tunnel and outdoor measurements to verify the assumptions of the SGS model.