Numerical Study of Fully Developed Turbulent Flow Within and Above a Dense Forest

摘要

Fully developed wind flow predictions within and above a dense forest were obtained using a computational fluid dynamics model. The model used a porous media analogy and a modified k-ε turbulence model where source terms were added to the momentum and turbulence equations. The mathematical model was solved using the software FLUENT 6.2. Experimental measurements from a black spruce forest, a jack pine forest and an aspen forest were used to validate the model. Two different ground boundary conditions were proposed: a full-slip boundary condition and a boundary condition that takes into account the forest ground roughness. Using these two boundary conditions, the accuracy of the proposed method was tested for forests with low foliage density. The innovative top boundary condition of Dalpe and Masson was validated with experimental measurements from Amiro. A sensitivity analysis was also performed on two important parameters: the drag coefficient and the leaf area density distribution. Results indicate that the proposed method simulated well the characteristics of wind flow within and above a forest. Results also indicate that, to obtain accurate results above the forest, it is necessary to take into account the forest ground roughness for forests with C_DLAI < 0.6.