Shelterbelts provide essential protection against wind erosion and soil degradation, as well as protection for fruit-bearing plants and crops from strong winds. Enhancing their sheltering capabilities requires optimizing their pattern and orientation, as well as defining their height and desired canopy shape, according to the desired performance. In this work, Large Eddy Simulation is employed to investigate the flow field and windbreak effectiveness of single and double-arranged shelterbelts characterized by different geometry and resistance to the air passage for neutral atmospheric condition. In particular, the canopy of the shelterbelts is modeled as an isotropic porous medium immersed in atmospheric boundary layer flow using the Darcy–Forchheimer model. Results show that a shelterbelt with a rectangular-shaped cross-section and a large canopy height results in the most significant reduction in mean wind speed and TKE, thus providing a large wind-protection region. As the spacing distance of double-arranged shelterbelts increases, the protection zones formed by both shelterbelts are reduced. The systematic comparisons of flow patterns, drag force coefficients, and windbreak effectiveness indicators of a series of single and double-arranged shelterbelts are essential for optimizing the design and management of shelterbelts.

The assessment of extreme wind loading on solar arrays plays a significant role in ensuring their safe operation under strong winds. Therefore, this paper investigates the extreme wind loading on solar arrays mounted on a flat roof by taking into account the wind directionality effect. The estimation process is conducted by using in situ wind speeds obtained from meteorological stations and wind loading coefficients on solar arrays obtained from wind tunnel tests based on the joint probability distribution of multiple variables and their conditional probabilities. This allows a discussion regarding how the extreme wind loading of solar arrays would be affected by such factors as the uncertainty of wind loading coefficient, the structural orientation of buildings on which solar arrays are mounted, and the directional characteristics of wind speeds. Finally, a comparison among the proposed methods, considering the wind directionality in current wind loading codes, is performed. The extreme wind loading determined by multivariate extreme value theory is found to be comparable to the corresponding estimate calculated according to the independent assumption of directional extreme wind speed. The results of this study provide a valuable reference for the design of wind-resistant solar arrays that takes account of wind directionality effect.

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° are smaller than those of 0°.

Spatially arranged cable systems and inclined hangers are becoming popular in shallow pedestrian suspension bridges to improve the lateral stiffness. However, the vertical motions of bridge decks under vortex shedding or pedestrian loadings may still cause annoying vibrations which may induce primary and internal resonances of the deck-cable systems. This study investigates the primary and internal resonances of the deck-cable systems with inclined hangers when the bridge deck suffers from vertical harmonic motion. A six-degrees-of-freedom (6-DOFs) mathematical model is adopted to simulate the linear and nonlinear dynamics of a cross-section of the bridge deck. Nonlinear behaviors of the structural system are systematically studied for the conditions under which internal resonance between two lower modes of the deck will occur. The analysis is conducted with the incremental harmonic balance method. The deck heaving mode in primary resonance does not exhibit distinct nonlinear property with different force magnitude, but notable nonlinearity is observed in the amplitude–frequency curve of the deck torsional mode. The nonlinear behavior of the structural system during the 1:2 internal resonances of the first two modes is also studied. Knowledge gained from this study may help in the vibration control of this type of bridge structures.

Shelterbelts are increasingly used to mitigate strong wind damage, but the complex canopy structures create challenges for numerical studies of windbreak effectiveness, such as the trade-off between computational cost and accuracy of results. To address these challenges and accurately investigate the downstream wind fields, most conventional studies represent shelterbelts as rectangular porous media with a uniformly distributed aerodynamic resistance coefficient. However, due to the vertical variation in canopy diameter and the irregular distribution of leaf density, the aerodynamic resistance of natural shelterbelts becomes nonuniform accordingly. To quantify the discrepancies arising from this simplification, this study first proposes a non-destructive approach to calculate canopy porosity profiles, which are further used to derive aerodynamic resistance at different heights. Then, by comparing the results obtained from the conventional and proposed approaches in Large-Eddy Simulations, the discrepancies caused by ignoring the vertical variation in canopy structures are analyzed. Finally, these discrepancies are further investigated for double-row shelterbelts. The results show that ignoring the vertical variation in canopy diameter leads to significant differences in windbreak effectiveness, especially for the downstream velocity and pressure fields at the top and middle heights of the canopy. The proposed approach provides a computationally efficient and more accurate representation of near-surface wind fields downstream of shelterbelts, thereby contributing to the accurate prediction of local wind fields for meteorological services.