Evaluation of the aerodynamic loads over isolated and clustered tree canopies using large eddy simulation

The mechanical resistance of trees is essential for their survival during strong wind events, enabling them to function effectively within an ecosystem. In this study, large eddy simulation is employed to investigate the aerodynamic characteristics of isolated trees with various crown geometries, as well as clustered tree canopies arranged in different patterns and spacing, under both normal and oblique wind directions. For each condition, the aerodynamic force coefficients are evaluated and the underlying flow mechanisms are discussed, also providing a comprehensive characterization of aerodynamic interference effects. As expected, results indicate that the effects of crown width and depth on the aerodynamic force coefficients of an isolated tree are very limited, although larger tree canopies generate stronger shielding effects and, thus, larger wakes. The mean and positive peak overturning moment coefficients of clustered tree canopies generally exhibit an increasing trend with the increase in spacing distance due to the enhanced channeling effects. The mean and positive peak overturning moment coefficients of clustered tree canopies are smaller than those of an isolated tree canopy, with interference factors ranging from 0.15 to 0.98. The corresponding interference factors for an oblique wind direction of 45 degrees are smaller than those of 0 degrees.