Assessment of the influence of plant shape and porosity on the wind shadow area based on numerical simulation

We systematically investigated the responses of wind shadow area characteristics to variations in plant porosity and u * / U h ( u * represents friction velocity and U h represents wind speed at a height of 0.25 m) across five plant shapes using numerical simulation. According to the windbreak requirements for mitigating soil wind erosion and sand transport, and meanwhile, considering the necessity for a continuous and complete wind shadow area, we defined the wind shadow area behind a plant as the region where u * / U h decreases by at least 50%, based on the simulation results. We find significant variations in the shape and size of the wind shadow area among the five plant shapes. Under identical conditions, the order of wind shadow area size is as follows: ellipsoidal plant > regular triangular plant > cylindrical plant > inverted triangular plant > umbrella-shaped plant. Furthermore, the relationship between the wind shadow area, porosity, and u * / U h for each plant morphology conforms to a multivariate linear function. The significance of this study lies in being the first to systematically analyze the response pattern of wind shadow area to varying u * / U h and porosity conditions across five representative plant types, providing a theoretical basis for optimal species selection in wind erosion control.