A comparative assessment of the prediction capability of transitional turbulence models was carried out in the chord Reynolds number range Rec=2.3×104−2×105 with the NACA 0012 and NACA 4415 airfoils. Four transition models based on the k−ω framework, i.e., the low-Reynolds number correction, Reθ−γ, γ and k−kl−ω were chosen to simulate the flow and aerodynamic characteristics. It is found that the prediction

An effective flow separation control method is urgently needed to improve the aerodynamic performance of the thick wind turbine airfoil. The purpose of the present study is to explore the effect of leading-edge protuberances (LEPs) on the aerodynamic performances for thick wind turbine airfoil during stall region. A direct force measurement technique employing three-component force balance was used

This paper focuses on the estimation of annual energy production (AEP) by simulating the flowfield on a complex terrain located in the northeast region of Brazil using different numerical approaches: CFD RANS with k-ε and k-ω turbulence models (WindSim), simple mass-conserving (WindMap), and refined mesoscale (SiteWind). The last two are run through OpenWind software. Wind observations from five meteorological

This paper proposes a numerical method to predict the ice accretion shapes and aerodynamic performance of rotating vertical axis wind turbine (VAWTs) under icing conditions. A multiple reference frame (MRF) and sliding mesh technique (SMT) are combined to efficiently reflect the unsteady icing effects on rotating wind turbines. The SMT calculates the flow field considering the rotational and unsteady

A testing device that was specially developed for large torsional amplitude vibrations was adopted to investigate the nonlinear post-flutter behaviors of a typical steel-truss girder bridge deck. Firstly, a series of free decay vibration tests of a narrow rigid rod model and a section model of the bridge were conducted in still-air to obtain mechanical properties and still-air induced aerodynamic properties

To study the aerodynamic effects and load spectra caused by high-speed trains passing through double-track tunnels, this paper uses unsteady, viscous, compressible Navier-Stokes equations and the Re-Normalization Group k-ε turbulence model with sliding grid technology for simulation. A dynamic model test is carried out to verify the calculation method and grid. This study considers the impact of the

Wind field characteristics were investigated with a non-stationary wind speed model at a bridge in a mountain valley, where five anemometers were set along the bridge span for long-term field measurements. The mean wind characteristics, such as mean wind speed and direction, were studied with a traditional steady wind-speed model, which showed the significant influence of the terrain on the mean wind

Ongoing urbanization has led to complexities in the urban terrain, increasing roughness length within the atmospheric surface layer, and introduced highly turbulent wind flow at pedestrian height. This research aims to explicitly examine the effect of wind flow turbulence on thermal perception under outdoor conditions. A wind tunnel with passive grid was used to introduce turbulence into simulated

Wind loads and structure of the flow field around an array of parabolic trough collectors (PTCs) were investigated using Delayed Detached Eddy Simulation (DDES) method. A scaled three-dimensional (3D) model was adopted and simulated using the ANSYS-Fluent software. Several pitch angles, including θ = 0°, 45°, 135°, and 180° and the stow mode with the pitch angle, θ = 90°, and flow Reynolds number of

A wind-tunnel study has been conducted to evaluate changes in the aerodynamic behaviour of stay cables of a bridge due to ice accretion from freezing rain and, due to different cable surface geometries. Numerical simulations were performed to predict the three-dimensional ice shapes resulting from freezing rain for a variation of environmental conditions: wind speed, wind direction, air temperature

This paper presents a study on aerodynamic properties of the upper segment of a high-voltage delta-configuration (cat-head) lattice transmission tower. These segments have been damaged in recent strong-wind events. A representative 1:100 scale specimen of the segment was subjected to wind tunnel tests. A computational fluid dynamics-based model was developed to simulate experimental observations. These

In this study, a practical method is proposed to predict the two-degree-of-freedom (2DOF) post-flutter behavior of a 5:1 rectangular section. For this method, a hybrid strategy in the time–frequency domain is introduced to obtain the time-history solution of the nonlinear coupled oscillator, and the nonlinear unsteady aerodynamic forces, described by the amplitude-dependent flutter derivatives, are

An active suction-jet flow control method was employed to suppress vortex-induced vibrations (VIVs) of a single-box girder based on a wind tunnel test. The flow structure around a fixed model was measured by time-resolved particle image velocimetry (PIV), and the stability of the flow field was evaluated in the controlled and uncontrolled cases according to the solution of the Orr–Sommerfeld equation

In this paper, the nonlinear characteristics of motion-induced aerodynamic forces on large-scale hyperbolic paraboloid roofs are numerically investigated using LES (large-eddy simulation). The mean and standard deviation (STD) of wind pressure coefficients on the rigid hyperbolic paraboloid roofs in the turbulent boundary layer are first simulated to validate the numerical models. Then the hyperbolic

A pressure field on a stationary bridge section with a clear signature from vortex shedding is obtained from a numerical simulation. The pressure field is subjected to modal decomposition using the snapshot prober orthogonal decomposition method (POD), the exact dynamic mode decomposition method (DMD) and a novel application of the eigenvalue realization algorithm (ERA) where the correlation functions

Coupling of multiple environmental factors in the engineering sector, in particular, joint distribution modeling based on a high-dimensional environmental dataset containing circular data is very topical. We propose a modeling framework applicable to the 3D joint distribution of circular-linear-linear (C-L-L) dataset consisting of a parametric model based on copulas and a nonparametric kernel density

Inspired by the study of Rao et al. (2019), the aerodynamics of a simplified frigate is investigated experimentally. The natural wake flow dynamics is shown to be bi-stable at zero yaw angles, at both the rear of the ship superstructure and the stern. The bi-stable dynamics is strongly weakened at the stern when the ship is lifted off the ground in the free-stream. Perimetric cavities of sufficient

Vacuum Tube Transportation (VTT) system utilizes the low-pressure environment to achieve aerodynamic drag reduction and reduce the energy consumption of high-speed trains. Within this system, even for trains operating at subsonic speed, the flow acceleration around the streamlined train may leads to local supersonic flow. The appearance of the supersonic flow will dramatically alter the flow field

When two circular cylinders are closely arranged in parallel, the downstream cylinder frequently exhibits wake-induced vibrations (WIVs). This study investigates the classifications of WIVs in various arrangements of cylinders by considering the generation mechanisms of WIVs through a series of wind tunnel tests. The generation mechanisms are defined through flutter and time-history analyses using

In this paper, a long-term probabilistic flutter analysis of long-span bridges, with consideration of the time-variant probability density function (PDF) of annual maximum wind speed caused by climate change and the deterioration effects of dynamic properties obtained by field monitoring data, is investigated. Estimated uncertainty, which occurs in probabilistic flutter analysis, is quantified by the

In this study, a Reynolds-averaged Navier-Stokes (RANS) numerical simulation with wind turbine simulated through actuator disk model was conducted to quantify the characteristics of wind turbine wake over two-dimensional Gaussian hills with different slope gradients. The simulated flow characteristics in the wind turbine wake, such as velocity deficit, wake expansion and wake centerline, were compared

The current research attempts to describe the association between the aerodynamic drag and flow structures induced by train running in time-averaged and time-dependant views. A ICE2 train model is used as the research object, with the flow field solved by Large Eddy Simulation (LES). The validation is carried out through comparison with existing research data, and grid independence study in terms of

In recent years, stay cables on cable-stayed bridges have been equipped with various kinds of lamps to lighten the cables at night. Large amplitude vibration of the stay cables of the Kuimen Bridge was observed after some rectangular lamps were installed. The mechanism and countermeasure of the cable vibration of this bridge were investigated in this paper. First, wind-induced responses of six stay

We explore the process of modeling aeolian snow transport around buildings by proposing a set of similarity requirements on simulating a single snow fall event with drifting. The similarity criteria are used to guide our wind tunnel tests from the particle selection to the simulation set-up, including the determination of test wind speed, snowfall intensity and transported snow profile. In parallel

Many parallel bridges have been recently designed and built around the world to accommodate the ever-increasing volumes of vehicle and rail traffic. Accordingly, the aerodynamic interference around the parallel girders becomes important to investigate for a more accurate estimation of wind-induced effects on bridges. In this study, a wide range of gap-width ratios (0–15) for parallel box girders are

Shape modification effectively reduces the wind loading and wind-induced vibrations of slender structures. Large-eddy simulation is used to investigate the flow around multiple square-like cylinders at a Reynolds number of 22,000. Based on a standard square cylinder, six square-like cylinders are simulated with sharp/rounded corners and straight/concave/convex sides. The combination of rounded corners

This study investigates the spatial coherence function of wind loads on the lattice frame structure through a simultaneous double high frequency force balance (HFFB) wind tunnel test. The wind forces on two segment models of the lattice frame structure are simultaneously measured by the wind tunnel test for several configurations of the models with different lateral and vertical distances. Coherence

This paper presents two novel semi-analytical models for predicting the aerodynamic performance of crosswind kite power systems (CKPSs), where the kite induction effects on the oncoming flow are taken into account. The blade element momentum theory forms the backbone of the models. The effects of reel-out ratio, solidity factor, rotor incidence angle, side-slip angle and tether drag are included in

Extreme wind events (e.g., thunderstorm downbursts) often present strong nonstationarities in terms of time-varying mean, amplitude modulation and frequency modulation. The stationary-wind assumption adopted in the traditional analysis framework for wind-induced structural responses may lead to severely biased estimates in nonstationary scenarios. Accordingly, advanced methodologies have recently emerged

The construction of a building inevitably changes the microclimate in its vicinity. Many city authorities request comprehensive wind studies before granting a building permit, which can be obtained by Computational Fluid Dynamics (CFD) simulations. When performing wind simulations, the quality of the geometry model is essential. Still, no available studies examine different geometry inputs' impact

To suppress the vortex-induced vibration (VIV) of long-span bridges, an active flow control method, i.e. the external suction-blowing method (ESBM), is proposed in this study based on the efficiency of the three-dimensional spanwise-varying flow control method and the suction/blowing flow control method. The method can be achieved by cyclically arranging suction and blowing on the undersurface of the

This paper proposes a new methodology to simulate wind fields that are non-orthogonal to the structure and to the traffic direction, and it presents the first wind–vehicle–bridge interaction (W-VBI) analysis framework to account for skew wind effects on the driving safety. The three-directional skew wind fields that are generated match well the target frequency content and correlation properties along

A key difficulty in air pollution dispersion modeling and quantifying fugitive emission fluxes of pollutants from open-pit mines is that the meteorological fields for such complex terrains cannot be reliably predicted using simplistic surface layer theory. In this study, transport phenomena over a shallow (100 m) and a deep (500 m) synthetic mine are predicted under thermally unstable, neutral, and

The flow patterns of the wake region of a rotationally oscillating cylinder were investigated experimentally by using the Particle Image Velocimetry (PIV) technique and dye visualization. The experiments were conducted at Reynolds number Re = 1000 and different values of oscillation amplitude (θA = 60°, 120°, 180°) and frequency ratio (FR = 0.8, 1.7, 3.3, 6.7). Dye visualizations, instantaneous vorticity

Reasonable gap spacings between adjacent train vehicle models are of great significance for the data accuracy during a wind tunnel test. In this research, crosswind flows around 1/8th-scale high-speed train models with inter-carriage gap spacings of 0, 5, 8, 10, and 20 mm are studied using improved delayed detached eddy simulation (IDDES) with the SST (shear-stress transport) k-omega model. The numerical

In order to find out the usability of the nacelle mounted light detection and ranging (lidar) for power performance testing under the condition of excavated terrain, an experimental investigation was carried out at the DBK wind farm on Jeju Island, South Korea. A nacelle lidar installed on a 2 MW test wind turbine was used with an 80 m tall met mast and a ground-based lidar for measuring wind conditions

A study of the aerodynamic characteristics of circular steel tubular lattice tower bodies in an ultrahigh-voltage direct-current transmission tower under skew winds is presented. The objective of the study, which was based on experimental and numerical methods, was to investigate the aerodynamic coefficients of tower bodies under both yaw and tilt angles. Scaled rigid models of tower bodies with a

The development of personal aerial vehicles (PAVs) using electric power distributed propulsion methods is rapidly growing. As the aerodynamic performance and flight stability characteristics can be significantly affected by multiple-propeller operation, aerodynamic analysis reflecting the power-on effect is required for design/development. Simulating all propellers using the general computational fluid

This study presents an unscented Kalman filter (UKF) approach for identification of linear or nonlinear flutter derivatives (FDs) of bridge decks from free vibration or buffeting response time history. The nonlinear FDs, which are dependent on torsional vibration amplitude, are represented in polynomial functions of torsional displacement. The augmented state variables of the two degrees of freedom

Arguably the most influential climatic load affecting the structural design of gulf coast refining and petrochemical facilities is wind. Despite this fact, little has been done to customize wind design for these unique facilities. This paper proposes a probabilistic model to predict the magnitude of shielding that is provided by the vast network of pipe rack structures that encircle these densely arranged

Large-eddy simulations (LES) can provide accurate predictions of wind loads on buildings, but their high computational cost, and the need to explore all wind directions with a 10° resolution, limits their use in the design process. Reynolds-averaged Navier–Stokes (RANS) have a low computational cost, but their accuracy can be compromised by the turbulence model and by the model required to retrieve

Models used for the wind tunnel testing of structures are commonly fabricated using additive manufacturing techniques, such as 3D printing; however, the corners of the models can sometimes be rounded with some radius of curvature R, rather than be perfectly sharp. Should the edge curvature of these models be too large, the aerodynamics of these models can be significantly altered leading to unrealistic

With the continuous improvement of train speeds, aerodynamic braking is a good choice to effectively reduce the braking distance. In this study, unsteady aerodynamic characteristics of vehicles with braking plates inside and outside the tunnel were evaluated by CFD using an improved delayed detached eddy simulation (IDDES). Mesh convergence studies were also performed, and results were compared with

The aerodynamic forces and near wake of a three-dimensional (3D) square cylinder with a height-to-width ratio (H/d) of 5 were experimentally studied in a low-speed wind tunnel at a Reynolds number of 3.4 × 104. This work aims to investigate the effects of turbulence intensity (=0.5%, 5.0% and 12.1%) on the forces and near wake. The wall boundary layer thickness is about 0.5d, unchanged in the three

The setting of tunnel linings is an effective way to reparation tunnel damage, which can also improve the tunnel surface structure. However, increased linings will change the cross-sectional area of the tunnel, affecting the pressure transients induced by the train passing through the tunnel. In this study, the non-circular linings' influence on the pressure transients is analyzed based on moving model

The complicated probability density function (PDF) characteristics of wind pressure, including its highly skewed, highly leptokurtic, and bimodal characteristics induced by sophisticated architecture, call for improved extreme-estimation models. Most existing methods are based on a unimodal PDF's underlying assumption and fail in highly non-Gaussian cases. Owing to the complete probabilistic information

An aeroelastic model design method of a complicated steel truss arch tower was proposed and the response features subjected to skew incident wind forces were presented via experimental approach. At the geometric scaling of 1:40, the bars of aeroelastic model were designed and manufactured with scaled appearance, of which the rigidities are scaled based on the classification grouping to the dimensions

With the previous knowledge of the effectiveness of single-split blades, questions arise about the effectiveness of a double-split configuration on horizontal axis wind turbine. To shed light on this question, a 3-D double-split finite-span configuration with S809 airfoil profile is designed based on the results of unsteady DES simulations of two families of single-split configurations. Firstly, the

Windblown sand flow interacts with a number of surface-mounted human-built obstacles. The wind-sand flow perturbation and resulting morphodynamic response of the sand bed cannot be assessed in analytical terms. Therefore, wind-sand tunnel studies around scale physical models are often carried out. They should be driven by physical similarity theory based on dimensionless numbers referred to the whole

Flow fields around reformed earth embankment windbreak walls (REEWWs) with five different porosities under crosswind were studied using the improved delayed detached eddy simulation (IDDES) based on the SST κ-ω turbulence model by computational fluid dynamics (CFD) in this paper. Based on the simulated flow field results, the finite element method (FEM) was adopted to analyze the wind-induced displacement

Owing to its significance in ensuring structural safety and occupant comfort, wind pressure on buildings has attracted the attention of numerous scholars. However, the characteristics of wind pressures are usually complex. This study employs an unsupervised machine-learning algorithm, clustering algorithms, to study wind pressures on buildings. Wind pressures on a single building and two adjacent buildings

Wind tunnel tests and the improved delayed detached eddy simulation (IDDES) were carried out to study the aerodynamic characteristics of a train with a wind barrier in different lengths. The results were obtained at 20° and 30° yaw angles, which are the highest realistic values for high-speed trains. The rationality of the experiment was assessed according to standards, based on which the accuracy

In this study, atmospheric motion vectors (AMVs) were derived from the satellite images predicted using a generative adversarial network (GAN) and a deep multi-scale frame prediction algorithm. The GAN was trained and tested with a sequence of the satellite images of a COMS satellite infrared-window channel under the 68 tropical cyclones. The inputs of the consecutive satellite images with 15-min interval

Windborne debris is a major cause of damage to the built environment during tornadoes. A fundamental step for quantifying this damage is to provide models that are able to describe the trajectory of the flying debris and thereby determine their impact location and associated momentum/energy. This goal can be achieved through the adoption of an appropriate three-dimensional (3D) six-degrees-of-freedom

The performance and durability of wall assemblies are greatly affected by the moisture load to which they may be subjected, in particular those arising from Wind-Driven Rain (WDR). Standard approaches for estimating such moisture loads assume 1% of the WDR load, whereas these loads have also been assessed from watertightness tests, although these assumed loads have been determined based on limited