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The computational effort for wind turbine design loads calculations is more extreme than it is for other applications (e.g. aerospace) which necessitates the use of efficient but low-fidelity models. Traditionally the Blade Element Momentum (BEM) method is used to resolve the rotor aerodynamics loads for this purpose, as this method is fast and robust. With the current trend of increasing rotor size, and consequently large and flexible blades, a need has risen for a more accurate prediction of rotor aerodynamics. Previous work has demonstrated large improvement potential in terms of fatigue load predictions using vortex wake models together with a manageable penalty in computational effort. The present publication has contributed towards making vortex wake models ready for application to certification load calculations. The observed reduction in flapwise blade root moment fatigue loading using vortex wake models instead of the Blade Element Momentum method from previous publications has been verified using a numerical wind tunnel, i.e. Computational Fluid Dynamics (CFD) simulations. A validation effort against a long term field measurement campaign featuring 2.5 MW turbines has also confirmed the improved prediction of unsteady load characteristics by vortex wake models against BEM based models in terms of fatigue loading. New light has been shed on the cause for the observed differences and several model improvements have been developed, both to reduce the computational effort of vortex wake simulations and to make BEM models more accurate. Scoping analyses for an entire fatigue load set have revealed the overall fatigue reduction may be up to 5 % for the AVATAR 10 MW rotor using a vortex wake rather than a BEM based code.

Wang, X.; Song, B.; Qian, Y., and Lao, J., 2020. Study of wind-induced vibration of a high-rise and thin-walled steel tower. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 78–82. Coconut Creek (Florida), ISSN 0749-0208.There are many high-rise and thin-walled structures in the coastal environment. These structures easily produce vibrations under the action of wind load. Thus, it is necessary to study the wind-induced vibration response of the steel tower. The AR model method is used to simulate the natural pulsating wind velocity spectrum in different return periods. In addition, the wind-induced vibration responses of the integrated steel tower are successfully calculated using a numerical wind tunnel method. The reliability of the numerical method is verified by onsite monitoring. The results show that the responses of displacement amplitude gradually increase along with height. The larger the wind velocity, the larger the displacement response of the structure. The maximum displacement does not exceed the limit for displacement of the structure. The stress decreases along with the height, and there is a mutation of stress at the position of the variable cross-section. The greater the wind velocity, the higher the stress. Therefore, for wind resistance evaluation of this steel tower, the bottom and variable cross-sections should be controlled by stress and the top should be controlled by displacement.

Unmanned Aircraft Systems (UASs) are gaining a lot of importance due to their inherent advantage of operating the aircraft with no onboard pilot. Though there are single and multi-rotor UASs, the later one is a popular choice for operations like surveillance and seed sowing in agriculture. This work emphasizes on carrying out computational fluid dynamic (CFD) simulations for investigating the flow around a quadcopter (UAS with four rotors) for different angles of attack (AoAs). Phenomena such as vortex formations and wake regions are studied. Quadcopter chosen for this work is a topology optimized 3D printed model. Numerical wind tunnel simulations are carried out for different wind velocities. Influence of relative propeller motion on each other is also studied. Stability of the quadcopter during lift and hovering stages is examined. From the results, it is observed that the stability of the quadcopter is dependent on the combination of AoA and velocity. Further, at lower ground clearances, the quadcopter is more stable than at higher altitudes because of the flow pattern.

The forces that wind exerts on a merchant ship, especially for a container ship that carries high stacks of cargo on board, can be very large; therefore, more accurate simulations than presently av...

Recent advances of the numerical wind tunnel result in a flexible methodological framework, which enables the fully-coupled simulation of wind-structure interactions considering the arbitrary and modular inclusion of additional devices into the system – such as added mass dampers – for the mitigation of vibrations caused by the wind flow. This feature could be seen as an add-on to what can be done with experimental methods and enables further possibilities when the predictive character of such simulations is used for structural design or even for the development and optimization of the additional devices themselves. The procedure promotes an approach fully-solved in time domain using a multiply-partitioned concept to be able to deal with the respective components in an efficient way. It is crucial to adopt a coupled approach and analysis in time as the involved systems can heavily influence each other. The systematic preparation of each module accompanied by coupled simulations is presented, which aims to ensure and enhance the quality of the overall solution strategy. The effectiveness and industrial relevance of the concept is presented on a tall building undergoing dynamic excitation due to vortex shedding with an integrated vibration mitigation device.

This paper numerically studied the Re-independence of turbulent flow and pollutant dispersion around five scaled building models. The RANS-based CFD model, hereafter called numerical wind tunnel (NWT) model, was validated by wind-tunnel experiments and applied to investigate the flow-structure independence on building Reynolds number (ReH) and roughness Reynolds number (Rer). The ratio of relative change (RRC) was used to evaluate the Re-independence with 5% selected as the threshold. The results show that the critical ReH (ReH,crit) is strongly affected by the building structure, particularly the building height. However, the value of the critical Rer (Rer,crit) in the pedestrian level plane changes very little with the different building models, which is suggested to be 25 in terms of the RRC criterion. Distributions of dimensionless velocity and concentration in the pedestrian level planes validated this suggested value. For the RANS turbulence models tested in this paper (high Reynolds number model and low Reynolds number model) the predicted value of Rer,crit is independent on the model. This work improves the understanding of Re-independence in the investigation of the flow and pollutant dispersion by using wind-tunnel experiment.

The hyperbolic paraboloid with two high and low corners is the most basic anticlastic double curved shape of tensile surface structures. However, this shape is currently not considered in the existing wind load standards and only very few investigations are documented in literature. Therefore, this study aims to map the mean aerodynamics over hyperbolic paraboloid roofs and extremely thin canopies to help engineers understand the general aerodynamics of these structures. In this study, scaled wind tunnel testing is performed on rigid models of a roof with enclosing walls and a canopy without enclosing walls to draft mean Cp-distributions and standard deviations for various wind orientations. These mean Cp-distributions are validated with the limited studies in literature and used to calibrate and benchmark a numerical wind tunnel, using CFD RANS simulations, that allows to further reduce the thickness of the canopy compared to the wind tunnel models. The numerical wind tunnel is used to study the mean wind load distributions for hyperbolic paraboloid roofs and canopies with different surface curvature for the most important wind orientations. The results in this paper show good agreement between wind tunnel experiments and CFD simulations, with similar variations as established by different studies of the Silsoe cube. First mean Cp-distributions obtained with scaled wind tunnel testing are presented for hyperbolic paraboloid canopies of only 5 mm thick, with similar mean net Cp and only slightly larger suction over the upper and lower face compared to the numerical results for a zero-thickness canopy. The numerical study of different surface curvatures indicates different geometrical patterns in the mean Cp-distributions when the flow starts to separate for highly curved hypars. In general, suction and pressure increase for higher surface curvature, with similar geometrical patterns in the mean Cp-distributions, as long as the flow remains attached. If the flow separates for highly curved hypars, the geometrical pattern differs and the mean Cp drops due to the different behavior of the flow. Finally, the presented mean Cp-distributions give insight in the aerodynamics of hypar roofs and canopies with different surface curvature and could form a basis for future analysis towards peak loads for the design of these structures.

The offshore structures that play a vital role in oil and gas extraction are always under complicated environmental conditions such as the random wind loads. The structural dynamic response under the harsh wind is still an important issue for the safety and reliable design of offshore structures. This study conducts an investigation to analyze the wind-induced structural response of a typical offshore deck structure. An accurate and efficient mixture simulation method is developed to simulate the fluctuating wind speed, which is then introduced as the boundary condition into numerical wind tunnel tests. Large eddy simulation (LES) is utilized to obtain the time series of wind pressures on the structural surfaces and to determine the worst working condition. Finally, the wind-induced structural responses are calculated by ANSYS Parametric Design Language (APDL). The numerically predicted wind pressures are found to be consistent with the existing experimental data, demonstrating the feasibility of the proposed methods. The wind-induced displacements have the certain periodicity and change steadily. The stresses at the top of the derrick and connections between deck and derrick are relatively larger. These methods as well as the numerical examples are expected to provide references for the wind-resistant design of the offshore structures.

Heliostats are sensitive to the wind load, thus as a key indicator, the study on the static and dynamic stability bearing capacity for heliostats is very important. In this work, a numerical wind tunnel was established to calculate the wind load coefficients in various survival stow positions. In order to explore the best survival stow position for the heliostat under the strong wind, eigenvalue buckling analysis method was introduced to predict the critical wind load theoretically. Considering the impact of the nonlinearity and initial geometrical imperfection, the nonlinear post-buckling behaviors of the heliostat were investigated by load-displacement curves in the full equilibrium process. Eventually, combining B-R criterion with equivalent displacement principle the dynamic critical wind speed and load amplitude coefficient were evaluated. The results show that the determination for the best survival stow position is too hasty just by the wind load coefficients. The geometric nonlinearity has a great effect on the stability bearing capacity of the heliostat, while the effects of the material nonlinearity and initial geometrical imperfection are relatively small. And the heliostat is insensitive to the initial geometrical imperfection. In addition, the heliostat has the highest safety factor for wind-resistant performance in the stow position of 90-90 which can be taken as the best survival stow position. In this case, the extreme survival wind speeds for the static and dynamic stability are 150 m/s and 36 m/s, respectively.

In order to describe an investigation of the flow around high-speed train on a bridge under cross winds using detached-eddy simulation (DES), a 1/8th scale model of a three-car high-speed train and a typical bridge model are employed, Numerical wind tunnel technology based on computational fluid dynamics (CFD) is used, and the CFD models are set as stationary models. The Reynolds number of the flow, based on the inflow velocity and the height of the vehicle, is 1.9×106. The computations are conducted under three cases, train on the windward track on the bridge (WWC), train on the leeward track on the bridge (LWC) and train on the flat ground (FGC). Commercial software FLUENT is used and the mesh sensitivity research is carried out by three different grids: coarse, medium and fine. Results show that compared with FGC case, the side force coefficients of the head cars for the WWC and LWC cases increases by 14% and 29%, respectively; the coefficients of middle cars for the WWC and LWC increase by 32% and 10%, respectively; and that of the tail car increases by 45% for the WWC whereas decreases by 2% for the LWC case. The most notable thing is that the side force and the rolling moment of the head car are greater for the LWC, while the side force and the rolling moment of the middle car and the tail car are greater for the WWC. Comparing the velocity profiles at different locations, the flow is significantly influenced by the bridge-train system when the air is close to it. For the three cases (WWC, LWC and FGC), the pressure on the windward side of train is mostly positive while that of the leeward side is negative. The discrepancy of train’s aerodynamic force is due to the different surface area of positive pressure and negative pressure zone. Many vortices are born on the leeward edge of the roofs. Theses vortices develop downstream, detach and dissipate into the wake region. The eddies develop irregularly, leading to a noticeably turbulent flow at leeward side of train.

The present paper reports an experimental/numerical study about the aerodynamics of sails in upwind conditions. This work is part of a wider research frame carried out in the recent years at Politecnico di Milano, involving numerical, wind tunnel and full-scale studies on the aero-hydrodynamics of sailing yachts. The experimental apparatus adopted in this work is the scaled-version of the full-scale setup adopted in the Sailing Yacht Laboratory (SYL) at the same institutions. More specifically, soft sails were tested in wind tunnel in close hauled conditions, properly equipped with thin and soft pressure strips at different sections of head and main sail. Therefore, simultaneous data about distributed pressure, aerodynamic forces and 3D flying shapes were gathered. Fine trimming were investigated during the tests to study the different effect on pressure distribution, performance and sail shapes. The measured sails geometry about the same conditions, fed the steady numerical simulations, based both on Vortex Lattice Method and Reynolds Averaged Navier Stokes equations, for comparison and validation. With regard to the latter, a sensitivity analysis on the simulation parameters was also reported in comparison to experimental results. Aim of this work was to improve the state-of-the-art with an extensive set of combined measurements and computations of different nature and objectives in order to provide a holistic view on the upwind sails aerodynamics.

This study presents an experimental and numerical investigation of the effects of tunnel blockage, defined as the ratio of the free portion of a wind tunnel cross-section with and without the rotor of a small-size (diameter 2 m) horizontal-axis turbine (HAWT). Experimental measurements were performed on three rotors with different number of blades, namely three, five and six, and different tip speed ratios, in the closed-loop closed-test chamber wind tunnel of the University of Perugia. Numerical wind tunnel simulations were performed at the University of Genoa through a steady-RANS method with SST k-ω turbulence model by means of the CFD solver OpenFOAM. The wind turbine was represented numerically by the actuator disc method. Simulations have been compared to experimental results for validation.

While large eddy simulation has several advantages in microscale air pollutant dispersion modelling, the parametric investigation of geometries is not yet feasible because of its relatively high computational cost. By assuming an analogy between heat and mass transport processes, we utilize a Graphics Processing Unit based software&mdash, originally developed for mechanical engineering applications&mdash, to model urban dispersion. The software allows for the modification of the geometry as well as the visualization of the transient flow and concentration fields during the simulation, thus supporting the analysis and comparison of different design concepts. By placing passive turbulence generators near the inlet, a numerical wind tunnel was created, capable of producing the characteristic velocity and turbulence intensity profiles of the urban boundary layer. The model results show a satisfactory agreement with wind tunnel experiments examining single street canyons. The effect of low boundary walls placed in the middle of the road and adjacent to the walkways was investigated in a wide parameter range, along with the impact made by the roof slope angle. The presented approach can be beneficially used in the early phase of simulation driven urban design, by screening the concepts to be experimentally tested or simulated with high accuracy models.

The practice of reproducing wind tunnel tests by means of CFD numerical simulations, which is known as numerical wind tunnel (NWT), is becoming quite common in many research fields of wind engineering. Wind tunnel tests can provide the indispensable validation data needed for CFD numerical simulations; at the same time, CFD can be considered a complementary support for wind tunnel tests in order to obtain a more comprehensive description of the flow field. In the present paper, NWT technique is applied to study the flow around and inside a multi-stage vertical-axis wind turbine (VAWT) surrounded by stator vanes. At first, the flow field has been studied in the wind tunnel by means of experimental tests. Then the experimental results have been used to validate a CFD model. The numerical model has finally been used to study and describe how the results obtained by means of the physical model can be extended to more general conditions.

The evaluation of the performance of a Darrieus Vertical Axis Wind Turbine is performed using an actuator line code. This allows to investigate the aerodynamics of the turbine and the interaction with the boundary conditions. Blade Pitch control, tip-effects modelling and blockage effects in an open-jet wind tunnel test section are studied and investigated. Pitch control allows to enhance the power extraction, tip effects allow to generate a more realistic model, while the modelling of the open-jet test section allows to validate the numerical approach on experimental data intrinsically characterized by not negligible blockage effects.

A three dimensional numerical wind tunnel based on the Navier-Stokes equations for viscous, incompressible fluid and LES method is established. Incoming wind field is generated based on the AIJ guidelines (2004). The numerical wind tunnel is validated against experimental results. A low-rise building with green roof is tested in the numerical wind tunnel. The results show that the green roof reduces the drag force of the building, cuts down the fluctuation near the roof, but has insignificant effect on the time-averaged velocity field.

To improve the flutter stability of a certain type fabricated steel truss bridge, a method of setting tuyere is put forward. Based on the two-dimensional 3 DOF coupling flutter method (2d-3DOF method), with the numerical wind tunnel established by computational fluid dynamics (CFD), the flutter stability control measures of tuyere is simulated. Through CFD numerical simulation, the flow field characteristics, flutter derivatives and critical flutter speed of origin and tuyere models are obtained. Through analysis, for the certain type fabricated steel truss bridge, the tuyere can improve its flutter stability. It illustrates the feasibility and reliability, and lays the foundation for further applied in practical projects.

In this paper, a modified inlet atmosphere boundary layer (ABL) which satisfies the turbulence model equations is applied to computational wind engineering. The new inflow turbulence boundary condition applied to simulating the flow in the cavity is verified that it is more in line with the actual flows, and then it is used to establish the numerical wind tunnel model to simulate the flow around high-rise buildings. The results are in good agreement with the wind tunnel experimental data, which show the modified ABL combined with Reynolds Stress Model (RSM) is able to better simulate the flow around high-rise buildings.

Zhang, X.-T.; Chen, X.-J.; Wang, Q.; Li, P., and Zhou, H.-M., 2019. Numerical simulation of buffeting response of cable-stayed truss bridge with unconventional load in port. In: Gong, D.; Zhu, H., and Liu, R. (eds.), Selected Topics in Coastal Research: Engineering, Industry, Economy, and Sustainable Development. Journal of Coastal Research, Special Issue No. 94, pp. 275–279. Coconut Creek (Florida), ISSN 0749-0208.Wind and waves seriously threaten the safety of structures in coastal ports. In this paper, the long-span cable-stayed truss structure in port for ore transportation along the coast is taken as the analysis object, with the static three-point force coefficient which obtained based on numerical wind tunnel simulation, the buffeting response of structure induced by turbulent wind load is studied by time-domain analysis method. The results show that the amplitude of buffeting response induced by turbulent wind load is larger than that of static wind load and it is also found that the increase of the main girder retaining wall and the operation load have great influence on the buffeting response of the structure. The research results can provide a strong theoretical basis for the design of the project and similar projects.

As long span suspension bridges have high towers, large flexibility and low damping, it is a must to consider the wind-resistant stability in bridge designs, especially for sea-crossing bridges where there are always strong winds. To ensure the traffic safety under strong winds, wind screens are often installed on the bridge deck to reduce the wind speed over the roadway. In order to analyze the influence of wind screens on wind-resistant capability and driving security for long span suspension bridges, CFD wind tunnel technique is adopted to analyze the flutter stability, the buffeting displacement and the wind environment of the bridge deck with and without wind screens. According to the analysis, the installation of wind screens could effectively reduce the wind speed over the roadway, but it would also weaken the wind-resistant capability of the bridge. The analysis results could be used as reference for the wind-resistant capability optimization and the wind screen design for long span suspension bridges.

Storm cause deformation and collapse of structure, endanger people's life and property security. In order to avoid or reduce the impact of wind load effectively, the paper mainly introduce wind tunnel test, numerical wind tunnel method, time domain analysis, frequency domain analysis and the research and application of domestic scholars.

In this paper, the wind field around the flat box girder of a long-span bridge under 0o attack angle was investigated by the numerical wind tunnel technique, which can not only get the distributions of the pressure, velocity and vortex in the flow field, but also obtain the various aerodynamic parameters of the bridges. The velocity profiles were obtained, and the coefficient of tri-component from the numerical simulations was in good agreement with that from the wind tunnel test, which demonstrated that it was reliable and feasible to utilize the numerical wind tunnel technique to simulate the wind field and certificate the coefficient of tri- component of the bridge.

Using the FLUENT software, this paper taking the wind load shape coefficient in the current code for the design of building structures as the comparison standard, have numerical wind tunnel simulation of the wind the surface wind pressure on arch roof. It focused on the effect of the different turbulence models on the numerical simulation, such as Spalart-Allmaras, Standard k ε, RNGk ε, Realizablek ε, Standard k ω, SST k ωand RSM. It provided reasonable reference for selection of turbulence model.

ANSYS Fluent software is used in the simulation analysis of numerical wind tunnel model for the upper Spar platform module. Design Modeler (DM), Meshing, FLUENT and CFD-POST are chosen in the numerical calculation. And DM is used to deal with and repair the geometric model, and Meshing is used to mesh the model, Fluent is used to set up and solve the calculation condition, finally CFD-POST is used for post-processing of the results. The wind loads are obtained under different direction and incidence angles. Finally, comparison is made between numerical results and empirical formula.

Large Eddy Simulation of NREL Phase VI wind turbine was performed in a virtual wind tunnel (24.4 m×36.6 m) in order to achieve a better understanding of the turbine wake characteristics. For this purpose, ANSYS-Fluent package was used to run the simulation using the dynamic Smagorinsky-Lilly model. For the purpose of validation, the pressure distribution at different span-wise sections along the turbine blade and the power produced by the wind turbine were compared with the published experimental results for the NREL phase VI rotor tested in the NASA wind tunnel with the same dimensions as in the model and a good agreement was found between the two. The airflow immediately behind the wind turbine was observed to be a system of intense and stable rotating helical vortices, which determined the dynamics of the far-wake. The system of vortices in the near-wake became unstable and broke down due to wake instability at a distance of five rotor diameters downstream of the wind turbine. This was defined as the boundary between the near- and far-wake regions. The collapsed spiral wake was found to spread in all directions in the far-wake resulting in the formation of the two pairs of counter-rotating vortices which caused the gradual increase of turbulence in these regions. The turbulence intensity in the wake was observed to increase immediately behind the turbine with a maximum of 12.12% at a distance of three rotor diameters downstream of the turbine, after which a gradual decrease in the turbulence intensity was observed in the near-wake regions due to wake instability. However, in the far-wake regions, due to counter-rotating vortices formed by the wake instability, the turbulence intensity showed a tendency to increase intensity. Finally the time-averaged wake velocities from the LES, with and without the blockage corrections, were compared with WAsP and a comparatively good agreement for the axial velocity predictions was observed in the far-wake.

The accurate evaluation of wind loads applied on floating offshore structures is extremely important as they are in specific conditions one of the dimensioning criteria for the mooring design. Nowadays these loads are mainly assessed through wind tunnel tests performed at model scale. Estimating realistic wind loads however, remains a big challenge. The complexity and associated simplification level of FPSO topside structures, the scale effects and the establishment of the atmospheric boundary layer imply that many simplifications are to be made. Typically, the FPSO topside is greatly simplified and equivalent blocs of wired frame are used. Today with the evolution of CFD software, and the increase of the meshing capacity, new scopes open to CFD. Aerodynamic simulations on complex FPSO structures are therefore now possible, but need specific developments and validations that are presented in this paper. The main objective of the work presented is to investigate the ability of CFD to evaluate wind loads on complex FPSOs topsides and to provide information on the impact of model simplifications made in wind tunnels. In a first stage, the numerical model was intensively validated by comparing its results to a wind tunnel test case. The numerical model was developed in order to ensure the quality of the results and enable a relevant comparison that was obtained with grids density up to 30 million cells. For this purpose, the geometric model used corresponds to the one used in wind tunnel. The same Atmospheric Boundary Layer was simulated and a thorough effort was performed to ensure the mesh convergence. In a second stage, more physical aspects of the wind tunnel methodology were investigated. Typically the accuracy of the blockage effect correction was evaluated by performing computations with and without blockage, and results were compared with classical corrections applied in wind tunnel. The impacts of the Atmospheric Boundary Layer on wind loads have also been investigated. Finally, the wind load contribution of each component of the FPSO was evaluated.

The most of Long-span stadium roofs are complex surface, the load norms cannot put forward the design requirements clearly in frequently. Determine wind loads need to use other means for help, while the numerical wind tunnel is one of the commonly be used to research methods in recent years. This paper introduces about the numerical simulation method of a long-span stadium roof surface wind pressure distribution , and based on FLUENT platform, a gymnasium as an example, the shear stress transport k - ω model (referred to as the SST k - ω model) on the roof surface wind pressure distribution of numerical wind tunnel simulation, analysis stadium roof surface pressure distribution law based on different wind directions.

Aiming at the wind load evaluation in the mechanical structure design of solar photovoltaic power generation station with sun tracking, a numerical wind tunnel model was established based on the computational fluid dynamics theory and finite element method. The 8-level wind velocity was applied in the model considering the mal-condition of reef islands and Gobi desert where the solar photovoltaic power generation station usually installed. From the numerical simulation results, the influence of elevation angle of the solar cells on the wind load was presented. To decrease the maximum wind load on the power station, the gap between solar cells was proposed as air vent in this paper, which has been adopted in a prototype machine, and more than 20% of the equipment weight has been reduced.

Using the FLUENT software, this paper taking the current code for the design of building structures as the comparison standard, have numerical wind tunnel simulation of the wind the surface wind pressure on low layer double slope roof. It focuses on the analysis of the effects of turbulence model selection on the numerical simulation results, such as Spalart-Allmaras、Standard k −ε、RNG k −ε、Realizable k −ε、Standard k −ω、SST k −ω and RSM, to provide a basis for the reasonable selection of turbulence models.

using the FLUENT software, this paper taking the current code for the design of building structures as the comparison standard, have numerical wind tunnel simulation of the wind the surface wind pressure on arch roof. It focuses on the analysis of the effects of three kinds of pressure velocity coupling algorithm on the numerical simulation results, respectively SIMPLE, SIMPLEC, PISO, to provide a basis for the reasonable selection of algorithm.

For numerical wind tunnel method has the advantages of low cost, fast speed, the more comprehensive results, the paper using CFD knowledge and the FLUENT software, using RSM turbulence model, SIMPLE algorithm, simulation class D landform, to have numerical simulation of average wind pressure coefficient for of the circular planar and saddle roof building ,which the current code for the design of building structures did not give, to provide reference for determining the average wind pressure coefficient of the circular planar and saddle roof building .

The existing “structure load code” did not give wind load shape coeeficient of rhombic plane and saddle-shaped roof .On this issue, numerical wind tunnel method has significant advantages such as low cost,fasting,collecting more comprehensive results.Using information of CFD and the software of FLUENT, using RNG - turbulence model, simulating a landform rhombic plane, the paper had numerical simulation of average wind pressure coefficient for rhombic plane and saddle-shaped roof building. It focused the effect on the numerical simulation for bending-span ratio. Finally it provided reference for reasonably determining the average wind pressure coefficient of rhombic plane and saddle-shaped roof building.

Air cooled thermal power structure is composed of spatial steel truss and steel-concrete tubular columns. Permeable “A” shape structure and wind-break wall are installed on its top. The wind load in the wind-break wall has great effect on its lower part. The structural wind parameters is not clearly stipulated in current load code. To solve the problems of wind parameter value in design and effectively evaluate the influence on wind-break wall form to the structural wind-resistant properties, three different wind-break wall forms are presented. Wind properties on an actual air cooled thermal power structure under three different wind–break wall forms are simulated with FLUENT software. Wind pressure law on “A” type structure and wind-break wall under different wind-break wall forms and at different wind direction angles is studied. Every division section shape coefficient of wind-break wall and “A” type structure under different conditions is obtained. The wind presure distribution law and the most reasonable wind-break wall form is obtained.

A brief introduction of Nanchang International Financial mansion manometry test model was stated first, And based on the Fluent software platforms, Wind pressure on the surface of high-rise building with the influence of adjacent buildings is simulated by computation fluid dynamics (CFD) methods. The results show that the numerical wind tunnel to some extent, more in line with the measurement results, but the errors in some parts are still large, relevant results will provide references for the research and the engineering practice.

Due to the increasing of wind disaster, structural wind engineering arouses more and more attention recently, with rapid development on spatial structure and continuous innovation of structural style. The main purpose of structural wind engineering is to calculate the wind pressure coefficients of structure. In this paper, the numerical wind tunnel method (NWTM), based on the Computational Fluid Dynamics (CFD), is applied to study wind load. The wind pressure coefficients of reticulated spherical shell with the 4.6m high wall were first determined, using the NWTM. The results are then compared with the wind tunnel test (WTT) and good agreement is found. The feasibility and reliability of NWTM were then verified. As the second example, NWTM is carried out to predict wind-induced pressure on reticulated spherical shell without wall. Further the distribution behavior of wind pressures on this kind of structures is discussed which could provide professionals the reference for the design of structure.

Problem of lateral driving stability of the automobiles passing by the vicinity of pylons of cable-supported bridges in condition of strong cross wind exists obviously because of the alternative wind environment above the deck due to complex flow fluid around the pylon and the deck. Based on numerical wind tunnel technology, the numerical simulation investigation of alternating wind environment above the girder near A-shaped pylon for main span of the steel truss girder cable-stayed bridge of Zhengxin Yellow River Highway-railway Bridge is carried out, considering wind barrier set up on the deck or not. The result shows that the original program has significant effect on wind speed amplification and mutation near the pylon domain in cross wind. Further investigation on wind barrier set up on both sides of the girder section or near the A-shaped pylon along the bridge gives that wind barrier near the A-shaped pylon is useful for reducing wind speed above the leeward deck near the pylon and weakening its mutation. Deeply, taken a medium-size commercial bus as an example, lateral driving stability of the automobiles passing by the leeward lane near A-shaped pylon is discussed through the dynamic response simulation of the vehicle controlled by ideal-driver under cross wind. The results confirms again that the wind barrier near the A-shaped pylon is good for driving safety of vehicles passing by the leeward lanes in vicinity of A-shaped pylon. In all, above work provides technical support for the final implementation of the wind barrier as an engineering measure.

This paper presents the results of full-scale numerical wind tunnel tests of wind pressure on structure roofs with suspension solar panels. Solar roof project is popularized in this century. Solar panels are suspended above the structure roof. So the wind load effect on the structure roof is varied. The wind tunnel experiments are often expensive. A 3D model is introduced and solved using ADINA. The wind pressure distribution coefficients are calculated.

The vortex interference mechanism on low Reynolds number between the canard and main wing of the canard-forward sweep wing (Canard-FSW) configurations is simulated numerically by employing the numerical wind tunnel method. The variations of aerodynamic characteristics of Canard-FSW configurations with different positions of the canard are investigated, finding that the aerodynamic interference and mutual coupling effect between the canard and main wing have made great contributions to the lift and stability characteristics of the whole aircraft. Canard can radically improve the surface flow pattern of the main wing. And its own vortex can have a favorable interference on the main wing and can effectively control the airflow boundary layer separation. At small angles of attack, the aerodynamic characteristics are sensitive to the positions of the canard and the main wing, but at high angles of attack, the aerodynamic performances of the configuration are not only related to the shape of the canard (forward or backward), but also with the size of control force as well as the features of the vortices generated above the main wing and the canard. The different configurations and vortices are illustrated using the velocity vector, streamlines and pressure contours.

In this paper, the wind load on an arc-shaped canopy roof was studied with numerical wind tunnel method (NWTM). Three-dimensional models were set up for the canopy roof with opened or closed skylights. The air flow around the roof under wind action from three directions was analysed respectively. Wind pressure coefficients on the canopy roof were determined by NWTM. The results of NWTM agreed well with those of wind tunnel test for the roof with opened skylights, which verified the applicability and rationality of NWTM. The effect of the closure of skylights was then investigated with NWTM. It was concluded that the closure of the skylights may increase the wind suction on the top surface of the roof greatly and should be considered in the structure design of the canopy roof.

The aerodynamic characteristic parameters are the foundation of vibration analysis of the overhead conductors. In this paper, a typical overhead conductor is studied using computational fluid dynamics (CFD) method. The smooth wire model and rough wire model are established, respectively, and the experimental analysis is carried out in the numerical wind tunnel. The aerodynamic parameters are obtained, and the influence of roughness of the wire surface is investigated.

Numerical procedure (Kratos) to replace wind tunnel tests.CFD and CFD with ALE (Arbitrary Eulerian-Lagrangian) analyses.Tests on Great Belt and bridge on Adige river cross section. The aim of the present study is to propose a reliable engineering procedure to analyze bridges subjected to wind loads by-passing the expensive wind tunnel tests thanks to numerical simulations. These exploit Kratos, a free multi-physic FEM code developed by the Kratos Team at CIMNE in Barcelona, and, specifically, an adaptation to the long-span bridge case of its numerical tool for simulation of in-wind ultra-lightweight structures developed within the uLites project (supported by the Research Executive Agency in the Seventh Framework Programme of the European Union, SP4-Capacities, Research for the benefit of SMEs, FP7-SME-2012 GA-314891, see http://www.cimne.com/websasp/ulites/). Time histories of the forces induced by the flow around the sections are used to calculate aerodynamic and aeroelastic parameters through statistical, frequencies extraction and fitting algorithms. Several analyses have been performed to derive rules for a reliable and stable evaluation of these aggregated parameters for engineering purposes. Results obtained for the sections of Great Belt Bridge (Denmark) and of the bridge on A31 highway over Adige river (Italy) are shown. Both static analyses (CFD procedure with fix boundaries) and imposed-displacements analyses (CFD with ALE) give results that are comparable with those coming from wind tunnel testing and from literature; evaluated parameters also manifest regular trends and values little influenced by CFD setting. These facts represent proofs of the reliability of the proposed procedure.

With the Messina project on the verge of realisation, attention should be directed towards state-of-the-art examples of large-span cable-supported bridges. Several bridges demonstrate the result of excellent engineering and design around the globe, all of which may provide useful indications of best practice for the design and construction of future bridges. This paper describes such issues exemplified by the Storebaelt (Great Belt) suspension bridge in Denmark. The Messina bridge will mark a giant leap with regard to maximum bridge spans, from the present 1990 m maximum of the Akashi bridge in Japan to the 3300 m main span of the Messina bridge. Furthermore, the new bridge will, as no other before, be subject to the effects of huge permanent loads, rail traffic, vehicle loadings, wind loadings and drifts, seismic effects, etc., all issues which need be dealt with utmost care, and which should use the technical specialist experience gained from the design and construction of recently built large cable-supported bridges. New technologies for: safety and reliability determination; risk management; construction materials; construction techniques; bridge deflections and stabilisation; comfort; numerical wind tunnel testing; dehumidification systems; and structural monitoring may contribute to an optimised design of future state-of-the-art bridges. Copyright © 2004 John Wiley & Sons, Ltd.

Previous studies have shown that Computational Wind Engineering (CWE) is still in itsrninfancy and has a long way to go to become truly useful to the design practitioner. The present workrnfocuses on more recent studies to identify progress on outstanding issues and improvements in thernnumerical simulation of wind effects on buildings. The paper reviews wind loading and environmentalrneffects; it finds that, in spite of some interesting and visually impressive results produced with CWE, thernnumerical wind tunnel is still virtual rather than real and many more parallel studies - numerical andrnexperimental - will be required to increase the level of confidence in the computational results.

A Genetic Algorithm (GA) has been applied to optimize a wing aerodynamic shape for generic subsonic transportation aircraft. A three-dimensional compressible Navier-Stokes (N-S) solver is used to evaluate aerodynamic performance of a wing. Although a GA has proved its ability to solve hard optimization problems, a GA coupled with a three-dimensional N-S solver has not been done yet because it needs large computational time even on the latest supercomputer. To overcome this difficulty, Numerical Wind Tunnel at National Aerospace Laboratory, a parallel vector machine with 166 processing elements, was used. In the optimum design obtained from the present GA, the design principles for the wing developed by existing theory and experience are found to be realized. This indicates feasibility of the present approach for the aerodynamic optimization in advanced computational environment.

Wind is a key factor when determining the safety of high-rise structures, such as buildings, chimneys, or towers. Using dampers to control wind-induced vibration is a safe, effective, and economical method for high-rise structures to employ. In this paper, viscoelastic dampers (VEDs) were used to reduce the dynamic responses of a 75-metre-high chimney. First, a simulation method for the stochastic wind field, based on the modified Fourier spectrum, was proposed. The method provided the accurate data of the wind velocity time history, which then simulated wind pressure through the use of a numerical wind tunnel. Then, the finite element model for the Madagascar chimney structure was built, and a wind-induced vibration analysis of the structure with and without VEDs was carried out under the simulated wind excitation. The optimisation – method, based on the genetic algorithm, was used to optimise the location of the VEDs. It was concluded that the accuracy of the modified Fourier spectrum method (MFSM) was greatly improved, when compared to the spectrum representation method of simulating the stochastic wind field. VEDs can effectively reduce the dynamic responses of chimney towers, especially for the displacement responses. In addition, the proposed optimisation method quickly determined the optimum positions and necessary quantities of VEDs to use, which yielded effective vibration mitigation.

The increase in both computational capability (CPU speed, memory capacity, etc) and flow solver/grid generation sophistication over the last two decades has allowed for computational simulations of so-called "real-world" problems to become more commonplace. While not meant to suggest that new developments in computational science and simulation have reached their limit, it seems fair to say that the analogy of the computer being used as a computational or numerical wind tunnel has been, at least to some degree, realized. With regard to aero-propulsion applications, the computational simulation of engine components (inlets, nozzles, compressors, turbines, etc.) has been quite successful, especially over the past 10 - 15 years. The topic of this paper is a qualitative demonstration of the scope that should logically follow component simulations, namely, that of simulating combined components on a system (or sub-system) level basis. While hypothetical in the sense that the actual hardware combination examined here does not exist, the results illustrate the interaction of the two components in the title and the importance of having the capability to conduct such system-level studies.

Plate-cone reticulated shell is a new type of space steel structures with good mechanical behavior and technical economy. In this paper, by using the wave superposition method, the fluctuation wind loads are simulated. According to the structural behavior of plate-cone reticulated shell, the structural shape factors of wind load for plate-cone reticulated shell were gained with numerical wind tunnel simulation based on Computational Fluid Dynamic(CFD) method through simulating wind field variation around plate-cone reticulated shell, and comprised with the common reticulated shell's shape factors of wind load suggested by the Code for loads, some important conclusions for plate-cone reticulated shell are obtained for practical design.