A large eddy simulation model applied to analyze the turbulent flow above Amazon forest

The occurrence of coherent structures (CS) above the Amazon forest is analyzed. To perform this study, a large eddy simulation (LES) model is used, which has been improved by the introduction of a drag force which is representative of a typical Amazon forest canopy. The results show that the flow is sensitive to the presence of canopy and an inflexion point is simulated in wind profiles. On the region between 1h and 4h several CS features associated with turbulent flow regarding pressure, momentum fluxes, skewness and vorticity fields are detected suggesting that “roll” structures arranged perpendicularly to the mean wind direction populate this region. Other interesting LES results were: (i) the skewness of the wind velocity has also a maximum value on the region, what indicates an asymmetric distribution of the wind velocity relatively to its mean value, a fact that might be associated with the generation process of the “roll” structures; (ii) the horizontal vorticity component transversal to the mean wind direction is greater than the vorticity components on the other orthogonal directions suggesting that “roll” structures move perpendicularly to the mean wind direction.