Incident Wind Research Articles

Towards an optimized design for an elevated cyclonic home using numerical simulations and active learning framework

This research presents a general optimization workflow and a geometrical parametric study using computational fluid dynamics (CFD) analyses in conjunction with a Kriging-based active learning strategy. Motivated by the concept of a wind-resistant “cyclonic home”, the present work conducts a systematic numerical wind study for a typical gable-roof elevated house structure across a parameter space consisting of varying incident wind directions and roof pitch angles. The house model is fully parametrized such that geometrical and mesh generation are automatically performed to facilitate the deployment of active learning for establishing a surrogate model of wind-induced forces. A wind force map is produced which reveals the relationship between the incident wind angle and roof pitch. From this, statistical analysis exposes which roof pitch angles offer greater wind-resistance, i.e., a roof pitch of θ=32.9° is found to provide the lowest mean force across all possible wind angles, whereas roof pitches of θ=12.7° and θ=45.0° yield the largest forces. The influence of the overhanging eave, a typical feature of such houses, is varied to understand its role on overall roof performance. Quartering winds are found to provide a greater contribution to overall roof forces as the eave length is extended. In contrast, for winds perpendicular to the roof ridge, its extension provides a relatively stable total force. These findings can assist a variety of stakeholders from engineering and risk assessment disciplines in pursuit of buildings resilient to high-winds due to tropical cyclones.

Numerical investigations on the start-up of a dual-tower system under crosswind: Collaborative and competitive effects

A three-dimensional numerical model is established to investigate the start-up process of a dual-tower system composed by two natural draft dry cooling towers (NDDCTs) under crosswind from 1 to 10 m/s. The coupled effects of tower spacings (1.5D, 2D and 3D) and incidence angles (0°, 45° and 90°) on the transients of the dual-tower system are checked. A simplified analysis identifies an enhancing factor EN and an impairing factor IM, which mutually determine the start-up duration of the dual-tower system. The numerical results present a general trend of the start-up process for a dual-tower system, i.e., it increases under mild crosswind from 1 to 4 m/s, peaks between 4 and 5 m/s and drops from 5 to 10 m/s. However, the dual-tower system at different tower spacings interacts with crosswind of different incidence angles in different ways during the start-up process. When paralleling with crosswind at 0°, both NDDCTs collaborate via the rising plumes. The collaborative effect accelerates the start-up process and is enhanced at a closer tower spacing. While perpendicular to the crosswind at 90°, both NDDCTs compete for the bottom inlet air via the shared zone. The competitive effect extends the start-up duration but is weakened at a larger tower spacing. While both effects exist simultaneously at a 45° wind incidence angle, leading to an increase of duration from 1.5D to 2D as the collaboration is weakened more, but a decrease of duration from 2D to 3D as the competition is decreased more. These conclusions will be useful for the request of larger cooling capacity and dispatchability on power blocks in hybrid energy systems.

Wind responses on twin box girder bridge deck using a fluid–structure interaction approach

Wind responses on a twin box girder bridge can be observed by a wind tunnel experiment or by having a full-scale setup if possible. Another possible approach is to go through a numerical approach, which is the CFD simulation of the atmospheric boundary layer surrounding the twin box girder bridge deck. A virtual wind tunnel CFD modelling simulation was carried out on the bridge deck using the Ansys Fluent FSI technique to find out the displacement of the bridge deck. The steady-state simulations were computed. The turbulence model was used to calculate the mean force coefficients as K-ω SST. It has been seen that steady simulation is needed to get the static aerodynamic coefficients right when modelling. Ansys ICEM CFD is used for meshing the bridge deck. In this study, the wind flow behaviour around the structure is analysed at different wind incident angles of − 10°, − 5°, 0°, 5°, and 10°. The pressure variations at different wind directions are mapped in the present work. Responses across and along the wind are also depicted. It was found that the drag coefficient was higher at low angles of attack, whereas the moment and the lift coefficients showed fewer values at large angles.

Effect of chemical regulators on the recovery of leaf physiology, dry matter accumulation and translocation, and yield-related characteristics in winter wheat following dry-hot wind

Dry-hot wind stress causes losses in wheat productivity in major growing regions worldwide, especially winter wheat in the Huang-Huai-Hai Plain of China, and both the occurrence and severity of such events are likely to increase with global climate change. To investigate the recovery of physiological functions and yield formation using a new non-commercial chemical regulator (NCR) following dry-hot wind stress, we conducted a three-year field experiment (2018–2021) with sprayed treatments of tap water (control), monopotassium phosphate (CKP), NCR at both the jointing and flowering stages (CFS), and NCR only at the jointing stage (FSJ) or flowering stage (FSF). The leaf physiology, biomass accumulation and translocation, grain-filling process, and yield components in winter wheat were assessed. Among the single spraying treatments, the FSJ treatment was beneficial for the accumulation of dry matter before anthesis, as well as larger increases in the maximum grain-filling rate and mean grain-filling rate. The FSF treatment performed better in maintaining a high relative chlorophyll content as indicated by the SPAD value, and a low rate of excised leaf water loss in flag leaves, promoting dry matter accumulation and the contribution to grain after anthesis, prolonging the duration of grain filling, and causing the period until the maximum grain-filling rate reached earlier. The CFS treatment was better than any other treatments in relieving the effects of dry-hot wind. The exogenous NCR treatments significantly increased grain yields by 12.45–18.20% in 2018–2019, 8.89–13.82% in 2019–2020, and 8.10–9.00% in 2020–2021. The conventional measure of the CKP treatment only increased grain yield by 6.69% in 2020–2021. The CFS treatment had the greatest mitigating effect on yield loss under dry-hot wind stress, followed by the FSF and FSJ treatments, and the CKP treatment only had a minimal effect. In summary, the CFS treatment could be used as the main chemical control measure for wheat stress resistance and yield stability in areas with a high incidence of dry-hot wind. This treatment can effectively regulate green retention and the water status of leaves, promote dry matter accumulation and efficient translocation, improve the grain-filling process, and ultimately reduce yield losses.

Effect of the incident wind angle in a frigate with Coanda active flow control

The aerodynamic environment around frigates can be complex. This can cause helicopter pilots operating on frigates to face risky situations during the recovery maneuver. In this paper, the introduction of active flow control using Coanda effect has been tested to improve flow characteristics above a frigate flight deck. Wind tunnel tests with Particle Image Velocimetry (PIV) have been performed in order to analyze the effectiveness of introducing Coanda effect at the hangar at four different wind over deck conditions. Applying Coanda effect on the upper part of the frigate hangar the re-attachment distance, and the recirculation areas are reduced. When the Coanda effect is applied also on the sides, the flow recirculation can be completely eliminated, especially for WOD angles different from 0°. The profiles of velocities at the height where the helicopter rotor operates are also corrected, making them uniform and similar to the free stream velocity. In exchange, there is an increase in turbulence intensity close to the hangar, without affecting the rest of the flight deck. The results have shown that Coanda effect clearly improves the aerodynamics over the flight deck where the helicopter operates, and it could help to increase the safety of helicopter operations around frigates.

An assessment of South American sediment fluxes under climate changes

Climate change can affect all levels of society and the planet. Recent studies have shown its effects on sediment fluxes in several locations worldwide, which can impact ecosystems and infrastructure such as reservoirs. In this study, we focused on simulating sediment fluxes using projections of future climate change for South America (SA), a continent with a high sediment transport rate to the oceans. Here, we used four climate change data yielded by the Eta Regional Climate Model: Eta-BESM, Eta-CanESM2, Eta-HadGEM2-ES, and Eta-MIROC5. In addition, it was evaluated the RCP4.5 greenhouse gas emissions scenario from CMIP5, which represents a moderate scenario. Climate change data between 1961 and 1995 (past) and 2021 and 2055 (future) were used to simulate and compare changes that may occur in water and sediment fluxes using the hydrological-hydrodynamic and sediment model MGB-SED AS. The Eta climate projections provided input data to MGB-SED AS model, such as precipitation, air surface temperature, incident solar radiation, relative humidity, wind speed, and atmospheric pressure. Our results showed sediment fluxes are expected to reduce (increase) in north-central (south-central) SA. While a sediment transport (QST) increase >30 % might occur, a 28 % decrease is expected to occur in the water discharge for the main SA basins. The most significant QST reductions were estimated for the Doce (−54 %), Tocantins (−49 %), and Xingu (−34 %) rivers, while the most significant increases were estimated for the Upper Paraná (409 %), Juruá (46 %), and Uruguay (40 %) rivers. We also observed that different climate change signals over large basins can impact the river water composition, which could lead to a new composition of the Amazon basin waters in the future, accompanied by a significant increase in sediment concentration.

Experimental Study of an Industrial Tower-Type Supporting Frame with Facades Subjected to the Stationary Wind Effect

Aerodynamic studies of canceled structures are important for design of buildings, analysis of air flows inside buildings, evaluation of buildings’ effects on air flow patterns of the adjoining area, and optimal choice of enclosing structures. The analysis of wind effects during the design of canceled structures is governed by codes and standards of general purpose. These statutory documents do not regulate the mounting procedure of wind protection screens, nor do they contain the analysis of wind effects on structures with different angles of attack of an incident wind flow. The codes prescribe aeroelastic model testing in special civil engineering wind tunnels during the design of such structures. The purpose of this research project is to analyze wind effects on the force and torque specification of a canceled structure at different wind effect angles accounting for the mounting sequence of wind protection screens. The subject of the article is an experimental aeroelastic study of wind effects on a canceled structure accounting for sequential mounting of wind protection screens on the structure’s facade. The obtained data will allow for the analysis of effects of the wind flow angle on internal forces of the structure, given that a change in its permeability is taken into account. At the initial design stage, experimental modeling of wind effects in a wind tunnel is thereby considered a structure model validation step. The relevance of the paper lies in the need to identify optimum operating conditions of canceled structures, subjected to a wind effect, to ensure safe and comfortable work of people and reliable operation of process equipment installed inside the facility.

Development of a flush ultrasonic probe for the measurement of the velocity and the angle of attack of an aircraft

In this work, a flush ultrasonic probe has been developed for the measurement of the velocity and the angle of attack (AOA) of an aircraft. The probe is made of one emitting transducer located at the center of a rotating stage and several receiving transducers located downstream, all transducers radiating in a normal direction perpendicular to the airflow. The determination of speed and AOA are deduced from the time of flight measurement of an ultrasonic wave between the emitter and the receivers propagating in the boundary layer. Particular attention was paid to the instrumentation as well as to the signal processing to enhance the ultrasound transmission and reception and to increase the signal-to-noise ratio. Results are reported for airflow velocities up to 127 m/s (460 km/h) both as a function of the emitter-receiver distance and as a function of the wind incidence angle. These experimental results are compared to simulations that estimate the time of flight between a source and a receiver. It is shown that ultrasonic waves propagate in the boundary layer and that the simulation code can predict the time of flight as a function of the distance and the angle.

Balcony design and surrounding constructions effects on natural ventilation performance and thermal comfort using CFD simulation: a case study

Despite natural light, near-façade structures’ impact on Natural Ventilation (NV) performance, reducing cooling demand, is usually ignored by designers. This article aims to characterize interactions between balconies’ design features (i.e. depth, unit level, and wind incident) and near-façade buildings on single-sided NV performance in a case study, representing medium to high-rise apartments in dominant cooling climates, utilizing validated Computational Fluid Dynamics (CFD) simulations. Results show that nearby buildings, even small structures close to the façade, significantly impact windward flow regime and indoor air movements. Nearby blocks might result in less air entering, which could be moderated by designing deeper balconies. Perpendicular wind incidents to the balcony opening may enormously improve single-sided NV performance. In contrast, wind incidents within higher degrees from perpendicular strongly reduce NV performance. This study provides designers with a method to characterize balcony design features’ effects on NV performance in apartments and improve it concerning urban design.

Triggering of galloping in structures at low Reynolds numbers

The fundamental mechanisms that are important for the triggering of galloping in a flow-induced vibration (FIV) system consisting of the flow past an elastically-mounted body (D-section, isosceles-triangular, rectangular) is investigated in this paper using three key-enabling methodologies: namely, high-fidelity full-order model/computational fluid dynamics simulations, modal analysis based on the determination of an data-driven model using the eigensystem realization algorithm, and use of the Den Hartog stability (galloping) criterion for the assessment of the aerodynamically unstable behavior of the system obtained from classical quasi-steady theory. The synthesis of the results from the application of these three key-enabling technologies is used to study the effect of the Reynolds number Re, the mass ratio m∗, the cross-sectional geometry and the angle of attack of the incident wind direction relative to the orientation of the elastically-mounted body on the suppression or initiation of galloping. In the application of data-driven modal analysis to a FIV system with coupled modes, the importance of identifying correctly which of the coupled modes correspond to the structure mode (SM) possibly taking into account mode switching is stressed, and the failure to do so is shown to lead to a significant underestimation of the value of the reduced velocity Ur associated with the onset of galloping. The range of values of Ur where the SM is positive is related to the flutter lock-in regime for smaller values of Ur (typically for Ur≤7) and to the galloping regime for the larger values of Ur (typically for Ur≥10). The application of data-driven modal analysis to a FIV system shows that increasing Re and decreasing m∗ has two effects: namely, enhancement of the coupling between the structure and wake modes and increases of the range of Ur values where the SM exhibits a positive growth rate. Data-driven modal analysis and the Den Hartog stability criterion is applied to explain the recently observed phenomenon of the collapse of galloping for a rectangular cylinder when the side ratio is decreased below a critical threshold value (between about 0.1 and 0.2). It is shown that galloping appears and disappears when the flat face of a body in directed into (windward of) or away from (leeward of) the incident wind direction. An investigation of the effects of the cross-sectional geometry of the body on the triggering of soft- or hard-galloping is undertaken.

Experimental Study of Wind Loads on Tubular Crossarms of Transmission Towers

The actions exerted by yawed wind on the crossarm substantially differ from those on the tower body due to the presence of the angle between the crossarm’s cross-section and the incoming flow, and this phenomenon deserves a better understanding. Focusing on the tubular crossarms with round-section members, this paper aims to determine insights into wind actions, as affected by various factors, such as the tower type, the mean width to mean height ratio, the solidity ratio, and the wind incidence angle, and thereby derive the wind loads for design. Accordingly, a succession of wind tunnel tests was conducted by using quadrilateral and triangular crossarm models with various solidity ratios and mean width to mean height ratios. The method of direct force measurement (DFM) is employed for the high frequency force balance (HFFB) test to attain the transverse and longitudinal forces on the crossarm simultaneously. It was found that the wind load coefficients increase with increases of the mean width to mean height ratio and decreases of the solidity ratio. Moreover, in the case of the incoming flow perpendicular to the crossarm face, it is concluded that compared to the quadrilateral crossarm, the triangular crossarm possesses a relatively smaller drag coefficient, provided a moderate mean width to mean height ratio of 1.19. Furthermore, an analysis of the experimental results shows that the skewed wind load factor specified in the relevant codes would overestimate the effects of the wind incidence angle and the variations in mean width to mean height ratio, which is evident in the tests but not considered in the codes. It is worth noting that the experimental results show that the crosswind force is pronounced, which is usually ignored in the skewed wind load factor-based approach. Comparatively, using wind load distribution factors seems to be more rational. Thus, the corresponding estimating equations are proposed for the wind load-distribution factors of the crossarms, which agree well with the experimental results. The developed equations would greatly facilitate the determination of wind loads on tubular crossarms.

Group riding: Cyclists exposure to road vehicle emissions in urban environments

A series of wind tunnel experiments were conducted in the University of Surrey’s Environmental Flow wind tunnel with a 1:50 scale of a typical London street canyon to assess the exposure of cyclists riding in a group to the emissions of polluting vehicles. A propane source emitted from an Ahmed body was used to model a car exhaust and a fast flame ionisation detector was used to measure pollutant concentration around four cyclists for multiple configurations of the source, cyclists, and wind directions. Two cases were investigated with a vehicle driving in front of a line of cyclists and adjacent to them (as if it were overtaking them).In the first case, for small wind incidence, findings confirm that the cyclists exposure decreases exponentially with their distance from the source with a small dependence on wind direction but largely independently of the riders position within the group. For large wind incidences, typical of urban canyons, the rider position within the group becomes more important.For the second set of experiments, with the vehicle positioned adjacent to the riders, it was found to be preferable for a rider to be in front of the group regardless of the distance from the source, as this results in lower exposure to pollutants. This is likely linked with the complex aerodynamic field generated by the group of riders that can trap the vehicle exhaust fumes amongst the cyclists, hence increasing the exposure.This research suggests that group riding should be considered when designing mitigation strategies to minimise cyclists exposure to road traffic pollution within urban environments, where busy and narrow cycle lanes often results in cyclists riding in line.

Wind Load Analysis on Gable Roof of Low-Rise Building

The effect of pressure because of the winds on the exterior of gable roof of a low-rise single-storey building has been analyzed in present research using CFD simulation. Roof slope, which is most important factor for safety of structure was taken into consideration. Many past researchers have studied roofed structures but the majority of these researches have been carried on flat roofs, hip roof, spherical roofs, pyramidal roofs. There is need of researches that analyses effect of winds on gable roofs as these kinds of roofs are generally more susceptible to wind damage. ANSYS ICM is used for modeling and meshing and ANSYS Fluent for simulation. Results are extracted here using CFD post. In this very study three models with slope ang 10°, 20° and 30° with same incidence angle 0° were examined. This study analyses the effect of slope of the roof and angle of incidence of wind. The streamlines of velocity around the building model and pressure coefficient (Cp ) contours on the surfaces of the roof are opted here to represent the results. When results were plotted it was found that pressure coefficients were switching from negative to positive as the slope of the roof increases and the formation of vortex on leeward gets complicated as we go on increasing the slopes.

Study on dust suppression performance of a new spray device during drilling and blasting construction in the metro tunnel

In order to solve the problems of excessive blasting dust concentration and portal pollution in a metro tunnel of a central urban area, a new spray device is discussed and its related parameters are studied in this paper. Through field sampling and an experimental spray dust settling platform, the particle size distribution characteristics of the tunnel blasting dust and the applicability of the nozzle are analysed. The tunnel and spray device are simulated by CFD software, and the variation laws of the droplet field concentration, velocity and particle diameter under different different incident angles, pressures and wind velocity are studied. The dust suppression performance of the new partition spray device is tested through field application. The results show that the droplet field generated by the spray device can effectively cover the whole section of the tunnel. At the same angle of incidence, the high concentration area first increases and then decreases in the direction away from the device, and the maximum concentration section gradually shifts away from the spray device. With the increase of the incident angle, the growth and attenuation trend of the high concentration region gradually flattens. The best incident angle for partitioning and dust reduction is 30°. When the nozzle pressure is set to 8 MPa, the parameters such as concentration, velocity and particle size distribution are the most appropriate. The effect of the air velocity at the air outlet on the characteristics of the droplet group generated by the device is not obvious. The field application shows that when the spray device is used, the dust reduction efficiency of respiratory dust and total dust at each measuring point is higher than 70 %. Compared with the original dust control measures, the average dust reduction efficiency is increased by 30 %, which can effectively improve the working environment of constructors in the tunnel and prevent the outward diffusion of dust.

Studies on Performance of Distributed Vertical Axis Wind Turbine under Building Turbulence

As a part of the new energy development trend, distributed power generation may fully utilize a variety of decentralized energy sources. Buildings close to the installation location, besides, may have a considerable impact on the wind turbines’ operation. Using a combined vertical axis wind turbine with an S-shaped lift outer blade and Φ-shaped drag inner blade, this paper investigates how a novel type of upstream wall interacts with the incident wind at various speeds, the influence region of the turbulent vortex, and performance variation. The results demonstrate that the building’s turbulence affects the wind’s horizontal and vertical direction, as well as its speed, in downstream places. The wall’s effect on wind speed changing in the downstream area is thoroughly investigated. It turns out that while choosing an installation location, disturbing flow areas or low disturbing flow zones should be avoided to have the least impact on wind turbine performance.

Coronavirus disease-2019 incidence and local wind speed: Is there any association?

Coronavirus disease-2019 incidence and local wind speed: Is there any association?

Key Questions of Solar Wind–Moon Interaction

Key questions on solar wind–Moon interaction are reviewed. As the nearest celestial body to Earth, Moon’s space environment is distinctive to Earth’s mainly because of lack of a significant atmosphere/ionosphere and a global magnetic field. From a global respective, solar wind can bombard its surface, and the solar wind materials cumulated in the soil record the evolution of the Solar System. Many small-scale remanent magnetic fields are scattered over the lunar surface and, just as planetary magnetic fields protect planets, they are believed to divert the incident solar wind and shield the local lunar surface beneath, thus producing unique local surface environment that is critical to activities of human beings/facilities, thus providing unique landing sites to explore the origins of lunar swirls and remanent magnetic fields. Evidences have hinted that this local interaction, however, may be also distinct with the interacting scenario on planets, and the specific process has not been revealed because of lack of in situ observations in the near-Moon space or on the ground. The global and local solar wind interactions of the Moon represent 2 types of characteristic interaction of celestial bodies with stellar wind in deep space, i.e., the interactions of nonmagnetized bodies and of small-scale magnetized bodies, both of which may occur on asteroids and Mars. The deep-space celestial bodies, either difficult or impossible to reach for human beings or artificial satellites, are hard to measure, and the exploration of the Moon can reveal the mystery of stellar wind interaction on these bodies.

On the Use of Dual Co-Polarized Radar Data to Derive a Sea Surface Doppler Model—Part 1: Approach

This article proposes a Doppler velocity (DV) model based on dual co-polarized (co-pol) decomposition of a normalized radar cross section of an ocean surface on polarized Bragg scattering and nonpolarized (NP) radar returns from breaking wave components. The dual co-pol decomposition provides a quantitative description of resonant and NP scattering, as well as their dependence on the incident angle, azimuth, and wind speed. Subsequently, the contributions of the facet (resonant Bragg waves and breakers) velocities, tilt, and hydrodynamic modulations due to long waves to the resulting DV can be quantified. The tilt modulation contributions to DV are estimated using the measured/empirical tilt modulation transfer function (MTF). The hydrodynamic modulations are mostly dominated by wave breaking and are estimated using a semiempirical model based on in situ measurements. In addition to the VV and HH radar data, which are required for dual co-pol decomposition and tilt MTF estimates, the surface wave spectrum is required in the DV determination for a given radar observation geometry. In this article, qualitative and quantitative consistencies are presented between the model simulations and the empirical CDOP model. In a companion paper, a DV analysis is presented to analyze the Sentinel-1 synthetic aperture radar measurements and collocated in situ measurements of surface wind and wave spectra.

Uniformity of water distribution in sprinkler irrigation mini-cannons in a high Andean community in Peru

The objective of the present work was to determine the uniformity of water distribution through mini-irrigation cannons in conditions of the Peruvian altiplano, applying the formulas for the Christiansen Uniformity Coefficient (CUC) and the Distribution Coefficient (DU) and to interpret the incidence of wind on water distribution at three different times during the day (5:30-7:30, 12-14 and 16-18 hours). Necessary climatological information, field rainfall tests, emitter pressure, and flow, wind speed were collected to evaluate their influence on water application. Variable CUC and distribution uniformity results were obtained at the level of four demonstration plots, the maximum and minimum CUC was 87.42% and 55.34%, while the DU resulted with a maximum of 80.79% and 26. 88% minimum; it is worth mentioning that in the last two schedules, results were obtained that show a poor water distribution; while winds less than 2 m/s favored the uniform distribution of water applied through the sprinklers, affirming that it was possible to obtain an acceptable water distribution uniformity at the plot level considering the irrigation schedule.

Exploring Wind-Induced Responses in Buildings with Non-uniform Plans

This study aims to investigate the wind effects on the structures with vertical irregularities. The project employs ANSYS numerical simulation to investigate the wind effects with different plan shape. The primary objective of this research is to evaluate the wind effects in terms of wind generated effects in the high-rise structure. The building dimensions are scaled down according to the ASCE wind tunnel test manual, maintaining a length scale of 1:100 for CFD investigation. This method provides essential insights into wind pattern circulation and pressure distribution across various wind incidence angles. The wind flow pattern surrounding the structure reveals characteristics of flow separation and the creation of vortices in wake regions. The study indicates that the plan layout and sizes of the model directly influence the distribution of wind pressure on its different faces. In both cases, there is positive pressure on the windward side