The overshoot phenomenon, where aerodynamic coefficients of bluff sections under accelerating flows exceed those in steady flows, is critical and controversial issue in the study of non-synoptic wind effects. Experimental simulation of accelerating flows requires complex dedicated facilities, which makes the investigation of key acceleration parameters affecting the aerodynamic overshoot still a challenging task. Therefore, numerical methods that allow easy control of acceleration parameters are urgently needed. In this study, aiming at verifying the accuracy of existing force evaluation approaches, we consider four types of accelerating inflows, namely, Linear, Hyperbolic, Sinusoidal, and Turbulent. The unsteady aerodynamic forces of rectangular cylinders with aspect ratios ranging from 3 to 16 are investigated using Unsteady Reynolds-averaged Navier–Stokes and Large Eddy Simulations. Sixteen different accelerating cases are considered to examine the effects of dimensionless acceleration parameters (ap) that defined by flow acceleration relative to velocity and deck height. Results show that accelerating flows cause drag overshoots well described by Morison equation but reduce vortex-induced lift forces. The ap is the key parameter governing drag overshoot, as it increases the absolute values of windward positive and leeward negative pressures. Additionally, the added mass coefficients are identified and an empirical formula is proposed to accurately estimate drag overshoot. The study provides guidance for the numerical simulation and drag estimation for bluff sections impinged by non-synoptic winds.

The vortex-induced vibrations (VIVs) of curved cable-stayed bridges differ from those of straight bridges due to two key factors. First, the superelevation introduces deck asymmetry and alters the effective angle of attack, leading to mechanisms responsible for VIVs that remain unclear. Second, spatial curvature modifies wind yaw angles and induces coupled vertical-torsional VIVs, complicating the mode shape correlation factor (MSCF) and making it challenging to assess VIVs solely from a straight sectional model. Investigating these effects through wind tunnel tests (WTTs) requires costly multiple sectional models, while fluid–structure interaction (FSI) simulations of in-service decks demand high computational burdens due to the fine mesh required for modeling barrier configurations. In this study, the effects of superelevation are investigated by combining sectional models, WTTs, and FSI simulations using two-dimensional (2D) unsteady Reynolds-averaged Navier–Stokes (URANS) and three-dimensional (3D) improved delayed detached eddy simulation (IDDES). Zero-thickness baffles are employed to model the barriers and accelerate simulations. Furthermore, the spatial curvature effects and MSCF are clarified by comparing sectional and full curved model WTTs. Results show that 2D URANS overestimates VIVs due to the inability to capture inner recirculation regions on the deck's lower surface, while 3D IDDES agree well with WTTs. Superelevation has unfavorable effects on VIVs by generating strong secondary vortices downstream of the central barrier at certain yaw angles, leading to conditions that might increase VIV amplitudes with respect to standard decks. The MSCF of 1.28 is recommended for coupled vertical-torsional VIVs, providing practical guidance for evaluating curved bridge VIVs using simplified sectional models.

The aerodynamic characteristics of a pitching flat plate encountering periodic gusts represent a fundamental problem in the field of aerodynamics and have motivated the development of theoretical gust-loading models. However, experimental validation of these models remains challenging, as it requires specialized facilities such as the active gust generator and forced-vibration system. Therefore, numerical methods that allow precise control of prescribed gust inflows and pitching motion are needed as a useful complement to experimental approaches. Aiming to validate the theoretical aerodynamic models and clarify the gust–motion interactions, this study investigates the unsteady lift and moment of a pitching flat plate in various periodic gusts using Unsteady Reynolds-averaged Navier–Stokes (URANS) simulations. Three types of periodic gusts in longitudinal, vertical, and bidirectional directions are synthetically generated to validate the Greenberg theory, the combined Theodorsen–Sears theory, and the combined Greenberg–Sears theory, respectively. Nine gusty inflow cases are considered to examine the effects of pitching amplitudes and gust characteristics on aerodynamic components and flutter derivatives (FDs). The URANS results match all three theoretical models at small pitching amplitudes. However, significant deviations occur at larger pitching amplitudes, particularly as increased vertical gust intensity breaks up the leading-edge vortices and generates strong secondary vortices, which in turn shift the phase of motion-induced moment and reverse the critical FD A2* from positive to negative. This study provides guidance for numerical simulations and aerodynamic models of an oscillating body subjected to gusts.

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.

Aerodynamic admittance functions (AAFs) are a key parameter determining the accuracy of buffeting analysis in long-span bridges. However, the presence of barriers and central gap complicates the aerodynamic response of in-service twin-box decks, thereby increasing uncertainties in AAF identifications when relying solely on traditional wind tunnel tests (WTTs). To improve the identification accuracy and reliability, the AAFs of a twin-box deck with barriers are investigated here by combining active wind tunnel tests, large eddy simulations (LESs), and field validations. Firstly, the AAFs in narrow-banded sinusoidal gusts are identified by combining the WTTs using the active gust generator and LESs. Then, the strongest wind event at the bridge site recorded over the service life of the bridge is simulated using LESs using a synthetic inflow to identify the AAFs under the action of broad-banded turbulent wind. The effects of barriers on AAFs are isolated by comparing the results obtained on the bare deck with those on the in-service geometry. Finally, time-domain buffeting analysis using four 1-h strong wind events is performed to validate the identified AAFs. Results show that the AAFs identified from active WTTs match well with LESs under both sinusoidal gusts and turbulent inflows, with values notably exceeding the Sears function and quasi-steady value of 1. The increase in AAFs caused by barriers is primarily attributed to reduced lift coefficient derivatives. Buffeting analysis using identified AAFs shows good agreement with field measurements, providing practical guidance for AAF identifications and buffeting estimations of in-service long-span bridges.

Porous fences are increasingly adopted for reducing wind loads on heliostats, and their deployment requires quantifying the effects of governing parameters (fence height H, porosity β, and fence-heliostat distance D) under a single and experimentally validated framework. However, the scale separation between the pores and entire fence-heliostat system makes pore-resolving large-eddy simulations (LES) computationally prohibitive, while reduced-scale wind tunnel tests (WTTs) require a dedicated fence model for each configuration. In this study, the fences in LES are represented by the pressure-jump approach, which reproduces the macroscopic windbreak effect without resolving the individual pores. First, this framework is validated against WTTs of a 1:10.5-scale heliostat with two fence heights at elevation angles of 0°–90°, reproducing the measured wake velocity profiles, mean and peak pressure distributions, and force coefficients. Parametric LES covering H = 0.4h–1.2h, β = 25%–76%, and D = 1.5h–12h (h is the torque-tube height) shows that fence height dominates, with the mean-load reduction becoming limited beyond H ≈ 1.0h, while the peak loads continue to decrease and the three parameters exhibit diminishing returns on the mean loads. The porosity effect is observed mainly near the fence: for the 0.4h-high fence, reducing β from 38% to 25% increases the velocity reduction at 1.0h downstream from 42.0% to 51.9%. These differences between porosities become less noticeable beyond about 3h, which indicates that porosity sensitivity weakens with the fence-heliostat distance. The results provide a validated, computationally efficient framework and quantitative criteria for optimizing porous fence deployment in heliostat fields.