Modeling plant canopy through numerical simulation of cylindrical array

Abstract

Vegetation is frequently utilized in windbreak engineering, yet the flow characteristics in the wake region and its interactions with airflow remain unresolved due to the heterogeneous geometry of canopy. By simplifying the canopy structure geometry as an array of cylinders with varying porosity, this works aims to reveal the flow characteristics and turbulence in the wake region of canopy flow using Large-Eddy Simulation. Meanwhile, the cylinder array is simplified using a porous-media model simulated by the k-epsilon turbulence model. A comparison of the two numerical methods reveals that employing the porous media model yields a better computational efficiency without much effect on the accuracy of the simulated steady flow region. More specifically, the RANS coupled with porous media model improves the computational efficiency by four times, while the maximal deviation in the steady flow region approaches 11%. We also analyze the dynamic mechanisms of turbulence structures in the wake region of the cylindrical array, and how vorticity fields vary with porosity. It is found that the increase in canopy porosity enlarge its protected area. Finally, an empirical model suitable for canopy vegetation is presented by analyzing the relationship between porosity and resistance coefficient.