Simulated Wind Fields Research Articles

Typhoon-Resistant Performance Assessment of Coastal Rural Residential Keel Brick Walls Reinforced with High Ductility Concrete

The keel brick wall belongs to the rural residential exterior wall unique to the southeast coastal region of China. The wooden keel inside the wall and the external tie members can improve the stability of the whole wall. However, due to the age of construction, the wooden keel inside the existing residential keel brick walls has basically rotted and lost the tie with the external members, which seriously reduces the stability of the whole wall. Moreover, the collapse of keel brick walls caused by typhoons has become more and more frequent in recent years, seriously endangering the lives and properties of residents. Therefore, it is necessary to carry out reinforcement and repair for the existing residential buildings with keel brick walls. In this paper, the keel brick walls of rural houses in Ningbo area were taken as the research object, a framework for evaluating the performance of keel brick walls against typhoons was established, tests on the lateral force resistance of keel brick walls reinforced with high ductility concrete and mortar were carried out. With the help of typhoon full-track simulation and wind field simulation technology, the 600-year near-surface typhoon wind speeds affecting Ningbo area were obtained. A joint probability distribution model of multi-directional extreme wind speed was constructed using t-Copula function to determine the mixed wind climate of Ningbo area. The extreme wind loads that keel brick walls can withstand under four types of reinforcement were finally given. The results show that the high ductility concrete reinforcement has great advantages over mortar reinforcement and avoids brittle damage of the masonry structure. The keel brick walls reinforced with single-sided mortar can withstand wind loads of a 3-year return period, the keel brick walls reinforced with single-sided high ductile concrete can withstand extreme wind loads of a 110-year return period, while the keel brick walls reinforced with double-sided mortar as well as double-sided high ductile concrete can withstand extreme wind loads of well over a 110-year return period.

Wind-induced response of an offshore wind turbine under non-neutral conditions: A comparison with Hywind Scotland

In this study, aeroelastic simulations of a 5 MW spar wind turbine are performed by using simulated wind fields that are representative of surface layer marine atmospheric turbulence under different atmospheric stratifications. The spar floater’s motion responses from the simulations are then compared with the observations from Hywind Scotland’s 6 MW spar wind turbine. The platform’s pitch and yaw motions from the simulations are consistent with the observations, in terms of mean wind speed and atmospheric stratification. The simulations and the observations show that a stable atmosphere induces the lowest platform pitch and yaw motions compared to neutral and unstable stratifications. Nonetheless, the discrepancy of platform motions between stable and unstable conditions is more pronounced from the observations than in the simulations. Uncertainties associated with the estimation of the atmospheric stability and the modelling of the turbulence’s co-coherence for lateral separation may partly account for the discrepancies between the observed and the simulated motion responses of the spar wind turbine.

A Mesoscale CFD Simulation Study of Basic Wind Pressure in Complex Terrain—A Case Study of Taizhou City

The basic wind pressure or the reference wind pressure for structural design varies greatly across complex terrain. Since only a few meteorological stations can provide adequate extreme wind speed records, it is very difficult to appropriately determine the basic wind pressure for a specific site without a long history of meteorological records. To solve this problem, a mesoscale CFD model was developed and optimized based on geographic information data for Taizhou and suitable turbulence models were selected for CFD simulation. The mean extreme wind speed and the corresponding direction at five main weather stations with long observation histories in Taizhou were used as the verification conditions to perform the CFD simulation of the extreme wind field. The maximum wind speeds of the rural areas, cities, and streets of Taizhou were obtained from the results of the mesoscale CFD simulations. Then, the 50-year return period reference wind pressures were calculated and could be used for the wind-resistant structural design of buildings for sites without a long history of meteorological records. The reliability of the results was verified by comparing the simulation results with the observation data at five main stations with a long history.

Application of power grid wind monitoring data in transmission line accident warning and handling affected by typhoon

With the increasing number of transmission line monitoring points, it is possible to obtain meteorological monitoring data of power grid, and the meteorological monitoring data of power grid can be further used to guide typhoon disaster early prevention, fault repair and disposal of transmission faults. This paper innovatively proposes a typhoon microscale (100 m) wind field simulation method suitable for the complex terrain conditions in different coastal areas of China, and uses the power grid meteorological monitoring data to improve the early warning accuracy and credibility in the local terrain space of typhoon disasters. The prediction robustness and accuracy of the scale reduction prediction model are improved through continuous observation and statistical correction, several engineering examples show that the method is correct and effective. The dynamic typhoon prevention strategy of the power grid and the timely adjustment of the power grid operation mode can be guided for the preliminary analysis of the cause of the transmission failure after the typhoon transit, so as to provide scientific guidance for the subsequent emergency repair. This method has a general practical and guiding value for the coastal power grid of the typhoon influence area.

CFD Numerical Simulation of Wind Field and Vehicle Aerodynamic Characteristics on Truss Bridge Deck under Crosswind

Due to the complexity and changeability of the wind field in deep-cut gorges, the vehicles on the bridge deck are easily affected by a strong crosswind. Thus, to accurately evaluate the wind field characteristics of a suspension bridge deck, the wind profiles of wind speed and angle of attack (AoA) and the vehicle aerodynamic parameters were investigated by the CFD. The results show that the shape of wind speed profile is mainly controlled by the AoA but less affected by the Reynolds number. The main girder's shielding effect can accelerate the local wind field, and the closer to the windward lane, the less the interference; thus, a suitable location of measuring points to represent the incoming flow is found. Furthermore, the equivalent wind speed based on the equivalent side force is generally larger than the value based on the rolling moment, and the responding value is greatly affected by the AoA. In addition, the vortex is a time-dependent phenomenon, the averaged flow field produced less force in the wake, but the high local wind speed variations may affect the traffic unfavorably. The results provide an essential reference significance for studying the local wind field characteristics of the bridge deck.

Application of metaheuristic optimization algorithms to evaluate the geometric and kinematic parameters of downbursts

Strong localized downbursts generated in thunderstorms can produce surface winds very dangerous for civil structures and infrastructures. Modelling and simulating such severe wind systems is therefore extremely important for structural safety and design wind speed evaluation. This paper deals with the downburst wind field simulation by means of an optimization algorithm that uses a downburst analytical model, previously developed by the authors, and two metaheuristic algorithms, namely the Differential Evolution (DE) and the Teaching-Learning-Based Optimization (TLBO), for the downburst kinematic and geometrical parameters evaluation. The optimization problem minimizes the relative error between recorded and simulated wind speed and direction time histories. A comparison is made between the performance of two algorithms for ten thunderstorm events measured in north-western Italy between October 2011 and October 2015. Both algorithms provide solutions which are coherent with the downburst parameters values present in literature. TLBO outperforms DE since it has a faster convergence rate to the optimal solution.

Influence of Phases of Coherence Functions on the Wind Field Simulation Using Spectral Representation Method

The wave passage effect is a measure of the wave passage delay due to the apparent velocity of waves, which is one of spatially varying properties of multivariate random processes. The phase of coherence function reflects the wave passage effect of wind fields. In the wind field, simulation by the spectral representation method, the classical phase formula, is not rigorous. This may affect the accuracy of simulation results and even cause incorrect simulations. In this study, the influences of the phase on stationary and nonstationary wind field simulations are researched and discussed in detail. Two schemes containing the classical phase formula and the separated phase scheme are compared in four types of wind field simulation. The qualitative analysis based on theoretical correlation function formula is first made to study the influence of the phase. Then, four numerical examples are utilized to quantitatively study the magnitude of the influence on the sample time history and correlation function of the simulated wind field. Results show that the classical phase formula will result in considerable simulation error for all four types of wind fields because it cannot completely represent the phase angle of a complex number.

A Study of a Severe Spring Dust Event in 2021 over East Asia with WRF-Chem and Multiple Platforms of Observations

In this study, we investigate the most severe East Asian dust storm in the past decade that occurred on 14–16 March 2021 based on the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) and a variety of site measurements and satellite retrievals. The dust emissions from the Gobi Desert, especially over Mongolia on March 14, are the dominant sources of this intense dust event. The maximal hourly accumulated dust emissions over Mongolian and Chinese areas reached 1490.18 kt at 07:00 UTC on 14 March and 821.70 kt at 2:00 UTC on 15 March, respectively. During this dust event, the accumulated dust emissions in coarse modes (i.e., bin 4 and bin 5) account for 64.1% of the total dust emission mass, and the accumulated dust emissions in fine modes (i.e., bin 1) are the least, accounting for 7.6% of the total dust emission mass. Because the coarse mode bins of dust dominate the emissions, the downwind transported coarse mode particles can affect the North China Plain, while the fine particles can only affect the desert source and its surrounding regions such as the Gansu and Ningxia provinces. Due to the dust emissions and the dust transport path, the high AOD areas are located in the Gobi Desert and Northwest China and the vertical spatial distributions of aerosol extinction coefficients have the same characteristics. We also found the model drawback of overestimating simulated wind speeds, which leads to the overestimations of dust emissions and concentrations, indicating the urgency of improving the simulated wind field.

Adaptability evaluation of boundary layer schemes for simulation of sea and land breeze circulation in the west coast of the Yellow Sea

In the study, a three dimensional Doppler Wind Lidar placed at a coastal city Rizhao in west coast of Yellow sea was used to evaluate the wind field simulated by ten different planetary boundary layer parameterization schemes (PBLS) in the Weather Research and Forecasting model. It is found that the characteristics of the simulated wind field are very sensitive to the boundary layer parameterization schemes used in the model, especially for the sea-land breeze (SLB). Analysis shows that Grenier-Bretherton-McCaa (GBM), Mellor-Yamada Nakanishi and Niino Level 2.5 (MYNN2), and Yonsei University (YSU) produced more realistic results of the three dimensional wind field, as well as the occurrence time, duration and heights of SLB. This is because the entrainment effect is adopted in the GBM scheme, which improves the radiation process between the ground and the atmosphere and ensures the accuracy of turbulent diffusion calculation caused by the differences of temperature and humidity in coastal area. The YSU scheme introduces a local gradient correction term, so that the non-local thermals brings the surface hot air to the middle and upper part of the boundary layer. This process increases the turbulent mixing induced by thermal forcing in the simulation of SLB. The MYNN2 scheme specifies the relationship between the length scale and buoyancy, turbulence scale and surface layer in turbulent kinetic energy equation, and introduces a set of closure parameters representing buoyancy and shear. However, the disadvantages of this scheme are that the influence of the underlying surface is not considered in detail, and the entrainment heat flux at the top of the convective boundary layer is underestimated.

Assessment of Permeability Windbreak Forests with Different Porosities Based on Laser Scanning and Computational Fluid Dynamics

Accurate modeling of windbreaks is essential for the precise assessment of wind protection performance. However, in most windbreak studies, the models used the approximate shape of the simulated trees, resulting in significant differences between the simulated results and the actual situation. In this study, terrestrial laser scanning (TLS) was used to extract tree parameters, which were used in a quantitative structural model (AdQSM) to recreate the tree structure and restore the wind field environment using the computational fluid dynamics software PHOENICS. In addition, we compared the bias, precision, and accuracy of porosity of Ginkgo biloba (with elliptical crown) and Populus alba (with conical crown), which have been commonly used in previous windbreak studies. The results showed that AdQSM has a high reduction rate and ability to reproduce the field conditions of the study area. After wind field simulation, the wind speed root mean square errors of the point cloud model at three heights (3, 6, and 9 m) were 0.272, 0.377, and 0.437 m/s, respectively, and the wind speed correlation coefficients r were 0.967, 0.965, and 0.937, respectively, which were significantly more accurate than those of the remaining two structures. Finally, the porosity of the windbreak forest obtained using the modeled sample plot showed a higher correlation with the wind permeability coefficient than that obtained using the existing approach. Windbreak models with three different porosities under the same conditions had different effects on the wind environment, particularly the location of the maximum wind speed reduction, variation of wind speed with porosity, and recovery rate of leeward wind speed. TLS can accurately extract windbreak factors and calculate the porosity, thus greatly improving the reliability of windbreak effect research in windbreak forests. This study provides a promising direction for future research related to the simulation of windbreak effects in windbreak forests.

A refined model of a typhoon near-surface wind field based on CFD

The simulation of near-surface typhoon wind fields is crucial for high-precision typhoon hazard assessments and thus of great significance for disaster forecasting, loss risk assessment and emergency management. The terrain correction method for simulating regional large-scale wind fields has a single correction method that cannot satisfy the requirements of refined risk assessment. This paper aims to use the advantage with regard to accuracy of the fluid dynamics mechanism model (CFD, computational fluid dynamics) in small-scale wind speed simulations and obtain a terrain correction method suitable for simulating regional large-scale wind fields by extracting the spatial variation of the wind speed over complex terrain. Specifically, typical mountains with different cross-sectional shapes and slopes are used to characterize the undulating terrain, and the CFD model is used to simulate and analyze the wind speed changes on the upwind and leeward slopes, at the mountain top, and in the downwind area under different initial wind speeds. The wind speed at these locations has a good quantitative relationship with the initial wind speed. Combined with the typical building wind load codes in China, the wind speed correction algorithm suitable for large-scale complex terrain is supplemented and improved. This paper presents the simulation results of three typhoons, and taking Typhoon No. 0713 as an example, a near-surface typhoon wind field simulation is performed. Compared with that of other models, the accuracy of the terrain-corrected simulation results by the method provided in this article is increased by 8.8–16.89%. Such CFD-based typhoon disaster near-surface wind fields can more accurately reflect the spatial distribution and intensity of typhoon wind hazards over large-scale complex terrain and can provide technical support for the loss risk prediction and assessment of forest resources, mountain forestry economies, crops and other vulnerable bodies during typhoon disasters.

Conditional simulation of 3D nonstationary wind field for sea-crossing bridges

This paper presents a framework for the conditional simulation of a 3D nonstationary wind field for super-long sea-crossing bridges based on wind speed time histories measured by limited anemometers on site. The variations of wind characteristics along the bridge deck with multi-elements are considered in this framework. The wind characteristics, including mean wind speeds, mean wind directions, turbulence intensities, turbulence integral scales, evolutionary wind spectra and spectral parameters, coherence functions and function parameters, at the measurement points are first obtained by analyzing the measured wind speed time histories. The wind characteristics are then extended over all the simulation points along the deck of the sea-crossing bridge using the spatial interpolation method and considering the variation of deck height above the sea level using the profiles of mean wind speeds, turbulence intensities and turbulence integral scales estimated from the measured wind speed time histories. After working out wind cross correlation functions, wind speed time histories at all simulation points over the sea-crossing bridge can be conditionally simulated. The proposed framework is finally applied to a real 22.9 km sea-crossing bridge under Typhoon Higos. The conditionally simulated wind speed time histories at all simulation points of the bridge are acceptable and consist a complete wind field which can be used for the buffeting analysis of the bridge.

Sensor Screening Methodology for Virtually Sensing Transmission Input Loads of a Wind Turbine Using Machine Learning Techniques and Drivetrain Simulations

The ongoing trend of building larger wind turbines (WT) to reach greater economies of scale is contributing to the reduction in cost of wind energy, as well as the increase in WT drivetrain input loads into uncharted territories. The resulting intensification of the load situation within the WT gearbox motivates the need to monitor WT transmission input loads. However, due to the high costs of direct measurement solutions, more economical solutions, such as virtual sensing of transmission input loads using stationary sensors mounted on the gearbox housing or other drivetrain locations, are of interest. As the number, type, and location of sensors needed for a virtual sensing solutions can vary considerably in cost, in this investigation, we aimed to identify optimal sensor locations for virtually sensing WT 6-degree of freedom (6-DOF) transmission input loads. Random forest (RF) models were designed and applied to a dataset containing simulated operational data of a Vestas V52 WT multibody simulation model undergoing simulated wind fields. The dataset contained the 6-DOF transmission input loads and signals from potential sensor locations covering deformations, misalignments, and rotational speeds at various drivetrain locations. The RF models were used to identify the sensor locations with the highest impact on accuracy of virtual load sensing following a known statistical test in order to prioritize and reduce the number of needed input signals. The performance of the models was assessed before and after reducing the number of input signals required. By allowing for a screening of sensors prior to real-world tests, the results demonstrate the high promise of the proposed method for optimizing the cost of future virtual WT transmission load sensors.

A heterogeneous accelerated simulation framework for wind field dynamic model

This paper proposes an efficient and extensible simulation framework for mid-fidelity wind field model based on heterogeneous architecture. The wind field model consists of 3-D wind inflow, wake dynamics, and wind turbine models. The CPU-GPU heterogeneous platform accelerates the 3-D wind inflow model simulation by performing large-scale parallel computing based on GPU. The CPU is utilized to dispatch the simulation and perform serial computing. Compared with the conventional simulation tool, the simulation speed of the 3-D wind inflow model is highly improved, which fulfils the requirement of the real-time wind field simulation. The hardware architecture of the framework is designed to be highly extensible by multiple computing nodes for 3-D wind inflow, wake dynamic, and wind turbine model. The extendability enables the ability for large-scale wind field simulation with high efficiency. A 5 km $\rm km$ × 2 km $\rm km$ × 0.35 km $\rm km$ wind field consisting of three wind turbines is used as the case. The case study was conducted and analyzed, proving that the framework can capture the detailed wake dynamic, wind turbine dynamic, and wind inflow dynamic. Meanwhile, the calculation speed of disturbed wind speed increased by 264 times.

Typhoon-Induced Fragility Analysis of Transmission Tower in Ningbo Area Considering the Effect of Long-Term Corrosion

The purpose of this paper was to investigate the influence of long-term corrosion on the deterioration of wind resistance of a steel transmission tower during its service life. An analytical model for predicting the long-term corrosion depth of carbon steel was established, and the corrosion depth of carbon steel in the Ningbo area was predicted based on the local atmospheric environment data. With the help of typhoon full-track simulation and wind field simulation technology, a joint probability distribution model of multidirectional extreme wind speeds was constructed using the t-Copula function to determine the typhoon climate of the transmission tower site. Finite element models of the ZM4 cathead transmission tower under 30/60/90 corrosion years were then established, respectively, according to the predicted corrosion depth of carbon steel in Ningbo. Three damage modes, i.e., minor damage, moderate damage and severe damage, corresponding to the transmission tower under wind loads, were defined, and pushover analyses were used to determine the limit values of each damage mode so as to obtain the typhoon-induced fragility curves of the transmission tower within 30/60/90 corrosion years. The results show that the increase in corrosion age leads to a deterioration in the nominal mechanical properties of the transmission tower components, making the damage probability to the transmission tower increase. Under the typhoon wind loads of a 50-year return period in the most unfavorable wind direction in Ningbo, the probability of moderate damage of the tower is within 10% and the probability of minor damage is controlled between 10% and 40%.

Typhoon-Induced Failure Process and Collapse Mechanism of Super-Large Cooling Tower Based on WRF-CFD-LS/DYNA Nesting Technology

There have been several cases of large cooling towers being damaged by wind in history. A typhoon has the characteristics of a strong wind field energy and large shear wind speed. This paper simulates the entire collapse process of large hyperbolic cooling towers by the action of typhoons and refines the typhoon-induced failure mechanism for cooling towers. Firstly, based on WRF-CFD wind field downscaling technology, a fine simulation of the near-ground multiscale wind field produced by China’s strongest typhoon “Typhoon Rammasun” is performed to extract effective three-dimensional (3D) typhoon load input parameters. Then, by loading the obtained 3D wind load on the finite element model, a pseudo-dynamic analysis of the world’s tallest cooling tower “Luan Cooling Tower” is performed based on LS-DYNA explicit dynamic analysis, and the typhoon-induced collapse process is simulated. Finally, the stress distribution and distortions of the tower and the response time history of key units are compared and analyzed to determine the collapse mechanism. The process of collapse begins with large deformation of the windward surface of the tower throat, which shows folds in the range of 62° on both sides. Eventually, collapse occurs due to uncoordinated deformation. The collapse mechanism can be divided into a bending arch mechanism and a suspension wire mechanism.

Fast simulation of fully non-stationary wind fields using a new matrix factorization assisted interpolation method

The classical spectral representation method and its improved versions have been widely used to generate non-stationary wind fields. However, they are not efficient for the simulation of non-stationary wind fields with time-varying coherence (i.e., fully non-stationary wind fields) due to the extensive computational demand regarding spectral matrix decomposition or harmonic superposition. To this end, this study develops a new matrix factorization assisted interpolation method, which is composed of an improved interpolation scheme and the monotone projected Barzilai-Borwein based non-negative matrix factorization (MPBB-NMF). Specifically, an improved interpolation scheme is firstly developed to quantify the desired distribution of time-frequency interpolation nodes, and only the decomposed spectra at these nodes are calculated by Cholesky decomposition. Then, MPBB-NMF with a fast global convergence is used to decouple these spectra into products of non-negative time- and frequency-dependent functions. Finally, one-dimensional interpolation is performed for these decoupled functions, which makes it possible to accelerate the harmonic superposition using a small amount of fast Fourier transforms (FFTs). Obviously, the proposed method realizes the decomposition of spectral matrix in the decoupling form. Besides reducing of the number of Cholesky decomposition and invoking FFT, its decoupling only aims at the low dimensional matrix and the interpolation merely involves a few decoupled items. Numerical simulation on the fully non-stationary wind field of a long-span bridge demonstrates the effectiveness and superiority of the proposed method.

Wind field numerical simulation in forested regions of complex terrain: A mesoscale study using WRF

The increasing human activity in forested regions requires a better understanding of the wind conditions. This paper aims to improve the wind simulation in forested regions of complex terrain, and thereby to investigate the effect of forest on wind characteristics. Considering the complexity of the surface, simulations were carried out covering different parameterization schemes sets using Weather Research and Forecasting model (WRF). The results indicate that Noah-MP scheme and YSU scheme are recommended for a mesoscale wind simulation in forested regions of complex terrain. Moreover, due to the complexities of land surface with seasonally-varied roughness length (RL) and leaf area index (LAI), localized LAIs and RLs would significantly improve wind field simulation. Comparisons demonstrated that the modified RLs, which can reshape the wind speed distribution, have greater impact than LAI on the wind field simulation in the near-surface level. The findings can be further exploited in the wind damage assessment for the infrastructures, as well as wind power assessment in forested regions.

An algorithm for rapid ground surface mesh generation used in complex terrain wind field simulation

In the study of wind engineering problems, it is of considerable importance to obtain accurate surface wind field characteristics. Surface features have significant impacts on the characteristics of small- and micro-scale wind field, so the fine reconstruction of terrain features is the basis of small- and micro-scale wind field simulations. However, since the GIS data obtained by satellite scanning cannot be directly used for CFD numerical simulation, the geographic information data is usually of considerable amount and contains a large number of waste points, thus difficult to be completed by manual modeling. To solve this problem, an automatic waste point repair algorithm and a grid aggregation method based on greedy algorithm are proposed, which can quickly and efficiently reconstruct the surface and generate the grid. Relying on the national numerical wind tunnel project and integrating the above core algorithms with the pre-processing and post-processing modules, a general and efficient surface mesh generation software ESM (Earth Surface Mesh) has been developed. Compared with the surface modeling and grid generation modules provided by other software, ESM has more comprehensive functions, and surface grid rapid generation technologies such as waste point data processing, grid adaptive refinement based on elevation change, high fidelity interpolation technology and partition splicing generation. It supports more interfaces and can generate structured and unstructured grids. The preliminary example shows that the surface grid generated by ESM meets the needs of wind engineering simulation.

Toward data assimilation of ship-induced aerosol–cloud interactions

Abstract Satellite imagery can detect temporary cloud trails or ship tracks formed from aerosols emitted from large ships traversing our oceans, a phenomenon that global climate models cannot directly reproduce. Ship tracks are observable examples of marine cloud brightening, a potential solar climate intervention that shows promise in helping combat climate change. In this paper, we demonstrate a simulation-based approach in learning the behavior of ship tracks based upon a novel stochastic emulation mechanism. Our method uses wind fields to determine the movement of aerosol–cloud tracks and uses a stochastic partial differential equation (SPDE) to model their persistence behavior. This SPDE incorporates both a drift and diffusion term which describes the movement of aerosol particles via wind and their diffusivity through the atmosphere, respectively. We first present our proposed approach with examples using simulated wind fields and ship paths. We then successfully demonstrate our tool by applying the approximate Bayesian computation method-sequential Monte Carlo for data assimilation.