Model-Simulated Influences of Shelterbelt Shape on Wind-Sheltering Efficiency

The authors report results of a numerical model used to simulate wind and turbulence fields for porous, living shelterbelts with seven different cross-sectional shapes. The simulations are consistent with results of Woodruff and Zingg whose wind-tunnel study demonstrated that all shelterbelts with very different shapes have nearly identical reduction of wind and turbulence. The simulations also showed that the pressure-loss (resistance) coefficient for smooth-shaped or streamlined shelterbelts is significantly smaller than that for rectangle-shaped or triangle-shaped shelterbelts with a windward vertical side. However, the shelter effects are not proportional to the pressure-loss coefficient (drag). Analysis of the momentum budget demonstrated that in the near lee and in the far lee, both vertical advection and pressure gradient have opposite roles in the recovery of wind speed. This behavior, combined with differences in permeability, is the likely cause of reduced sensitivity of shelter effects to shelterbelt shape.