NUMERICAL SIMULATIONS OF SHELTERBELT EFFECTS ON WIND DIRECTION

neutral boundary layer nonhydrostatic numerical model is used to deter mine the characteristics of shelterbelt effects on mean wind direction and to study the processes causing wind rotation when air passes thro ugh a shelterbelt. The model uses a turbulence scheme that includes pr ognostic equations for turbulence kinetic energy and a master length s cale proposed by Mellor and Yamada. The simulated results are in quant itative agreement with Nord's field measurements. The spatial variatio n of wind rotation and its dependence on incident angle and shelterbel t porosity is analyzed Dynamic processes of the wind rotation and its interactions with drag force and pressure perturbation are also discus sed. It is concluded that shear of wind direction should be considered , along with shear of speed, in determining turbulent fluxes in the vi cinity of a shelterbelt.