Proceedings of the 9th National Conference on Wind Engineering

Tornadoes have been reported in the USA, Canada, China, and Europe over the past several decades. While not very common, yet there have been sporadic occurrences of tornadoes in India (e.g., West Bengal tornado outbreak, 2021). Although the occurrence of tornadoes and the economic and human losses seem to be a cosmopolitan problem, the research efforts to develop a better understanding of wind loading of structures during tornadoes are limited to select research groups of prestigious universities in the world. In that regard, the authors have previously pursued CFD modeling work on tornadoes using in-house codes. However, there are inherent challenges in customizing in-house codes if it has to be adapted to user-specific cases. Thus, for the wider accessibility of tornado simulation tools to students and early-career researchers, the details of the implementation of a simple CFD tornado simulator model using open-source software OpenFOAM is discussed in this contribution.

Wind tunnel experimentations have played a vital role in determining the aerodynamic loads for the design of aircrafts, tall buildings, bridges, etc. With the advent of unmanned and autonomous flying devices, the role of wind tunnel testing becomes even more critical. The role will now not only include determining the aerodynamic loads but also testing the autonomous capabilities and the ability of the autonomous flying device to react to the changes in wind speeds and directions. The objective of the current work will be is to construct and calibrate one such low-speed wind tunnel that will have capability to generate different wind velocity profiles along with gust. The test section of the wind tunnel will of a cross-sectional size 1.2 m × 1.2 m and 2.4 m long. The wind flow through the test section will be powered by a grid of 10 × 10 DC fans, each having a capacity of 250 CFM.

Flow around a square cylinder with corner fins was studied to investigate the aerodynamic characteristics of the same at different angles of attack. This study simulates flow around typical building structures employed in practical situations. Flow was studied in a flow visualization water channel at a Reynolds number of 2100 with blockage ratio less than 10%. In this study, vortex formation length and vortex shedding frequency are primarily measured for various cases. From these two parameters, other aerodynamic parameters such as coefficient of base pressure, coefficient of drag, circulation content of a shed vortex, and total circulation shed at the separation point are deduced. It is found that corner fin considerably modifies the flow field of a square cylinder. Furthermore, body angle of inclination brings additional changes in the flow structures around it and in the associated aerodynamic characteristics.

In the lowest layer of the atmosphere, the wind is slowed down by the drag effect of the numerous features on the earth’s surface such as vegetation, ground roughness, and human construction. Within this layer, wind speed generally increases with height until the top of the layer is reached, where surface drag is no longer a factor. However, mountains and valleys in the vicinity of a study site can have a significant impact on wind patterns, deviating from the typical wind characteristics seen in flat, open, suburban, or urban areas. This paper details the methodology of accounting for the wind characteristics at a site surrounded by unusual terrain in the wind tunnel.

Vertical-axis wind turbines are more advantageous than their horizontal-axis counterparts when placed in an array. They have the maximum capability to harvest the abundantly available source of wind energy. The presence of VAWT in the region of the onset of the atmospheric boundary layer, i.e. the earth's surface, and in offshore places where continuous unsteady airflow is encountered, has severe structural impacts in the form of vibrations that lead to system failure. To put a restraint on the problems caused, in this study, the leading-edge protuberance blades (LEP) are introduced on the VAWT instead of the previously available straight blades and are tested in the axial wind blower present in the Turbulence and Flow Control Laboratory at SASTRA Deemed University. It is to understand the diversification of the vibrational characteristics measured on the main shaft of the VAWT with the help of the triaxial accelerometer connected to a versatile data acquisition system. The results revealed that the LEP suppresses the evolution of the dynamic stall vortices considerably at low tip speed ratios, which in turn reduces the vibration on the turbine shaft, leading to the prevention of catastrophic failure of the system with the corresponding increase in turbine efficiency.

Wind energy has enormous potential to fulfil industrial and other power requirement demands specifically in remote areas. The amount of power generated from the wind turbine depends on several factors, namely wind speed, wind direction, rotor area, the height of the tower, etc. As the wind speed is highly dynamic, it highly affects the power generation capacity of the windmills. Thus, it is highly desired that wind shall be monitored as well as forecasted earlier to prevent any sudden ups or downs in the power generation. This manuscript presents a regression-based methodology to predict the wind speed using XGBoost and AdaBoost regression learners. Their learning capabilities have been compared using mean absolute error. XGBoost is found to have lesser value of MAE at 0.392. Parallelly, N-Beats, the time series forecasting model is trained to forecast the wind speed. This way, the present study showcases the utility of time series forecasting method to accurately predict and forecast the wind speed.

Alongwind and acrosswind response of tall rectangular buildings have attracted the attention of researchers in the last 50 years or so resulting in many useful findings. In order to get a deeper insight into the phenomenon related to tall building aerodynamics, experimental investigations on the model of a 240 m high rectangular multi-storey building with plan dimensions [width (b) × depth (D)] 24 m × 48 m (b/D = 2.0) and H/√(bD) = 7.07 have been carried out to study its response in two types of terrains, viz. city outskirt (α  = 0.18) and city-centre (α = 0.30). The response of the model has also been studied in three grid generated flow conditions, to investigate the effect of ‘turbulence’ parameters. The results reported particularly bring out the effect of flow parameters like Turbulence Intensity ‘I_u’ and Integral Length Scale ‘L_ux’, on the building response.

Each year there has been a steady rise in vehicles plying on roads leading to an increase in roadside pollution. The condition is grimmer in urban sectors and metro cities. The dispersion of vehicular pollution is essential for the health of pedestrians and nearby societies. Factors like street canyon geometry and meteorological conditions play a significant role in dispersing pollution. One of a typical urban road settings includes a T-intersection canyon having buildings alongside it. The current work attempts to numerically study the wind pattern in the proximity of a T-intersection street configuration. The study investigates the effect of incoming wind velocities and building aspect ratio on the turbulence levels and flow zones adjoining the street canyon. It is observed that the flow regime for the configuration when the ratio of building height and street is one is skimming, while the bulk flow does not enter the canyon. The changes in the configuration lead to variations in the formation of distinct vortexes that are stable and isolated. The analysis of velocity profiles shows sharp gradients at the tip of the building but tends to decrease slowly away from the ground.

The flow past a circular cylinder is an important problem of investigation in applications such as structural engineering (bridge structures, tall buildings, chimneys, etc.) and aeronautical engineering (bluff body aerodynamics). CFD based on the Finite Volume Method implemented in the solver Fluent shows that aerodynamic coefficients while predicted with remarkable accuracy for the two-dimensional, steady, viscous flow past a circular cylinder case revealed errors or discrepancies in the prediction of von Kármán vortex street (and associated periodicity of lift and drag) at the Reynolds number range of 46–48. The reason for the discrepancy is investigated with a focus on predicting von Kármán vortex street at Re of 48, by making different grid design considerations, viz., varying the blockage ratio, upstream distance of cylinder to inlet, downstream distance from cylinder to outlet boundary and mesh element size parameter. Although the known flow characteristics such as fluidic unsteadiness, force oscillations and vortex shedding predictions existent at this Re were never predicted, the mean drag coefficient was predicted in all cases with high degree of accuracy. The recommendations and conclusions drawn from the study could now be applied to different fluid flow problems. The earlier obtained results provided guidance on how to find solutions to different applications as well as perform more complex fluid flow simulations effectively, with minimal error and effort.

Aerodynamic forces are used by all wind turbines to capture wind energy. Lift vector acts normal to the relative wind, whereas drag force acts parallel to the relative wind. The factors taken into account include the swept area of the turbine, the density of air, the wind speed, the aerodynamic efficiency, and the coefficient of power which is directly proportional to blade tip speed. The research demonstrates that the operational aerodynamic characteristics have a direct impact on the power produced, which will encourage researchers to concentrate on the most important aerodynamic factors for developing and manufacturing the next generation of wind turbines. At last, the results are examined whether the flow parameters meet the aerodynamic requirements for the design of industrial wind turbines.

Problems in wind engineering are addressed using computational techniques, or computational wind engineering (CWE). Although Computational Fluid Dynamics (CFD) is just one component of CWE, it has up to now been used as a main tool. The vortex formation in wind turbines has to be studied certainly in order to avoid the formation of induced drag and methods that are required to minimize the effects of vorticity. The boundary layer formation analysis and vortex formation analysis in the blades of industrial wind turbines are solved using numerical techniques. To achieve the necessary flow characteristics, such as vortex generation and boundary layer creation in the wind turbine blades during flow separation, the lift-to-drag ratio, pressure coefficient, variation of lift with respect to the angle of attack, variation of drag with respect to the angle of attack, and intensity of induced drag brought on by vortex formation are studied using CFD. It also encloses the control and minimizing techniques of vorticity generation and boundary layer formation.

Wind load causes shear lag in high-rise tubular buildings. A building’s stability may be adversely affected by this phenomenon when tension inevitably develops in upper story columns. The amount of shear lag depends on several factors, such as the building layout, the spacing between the outer peripheral columns, and the load applied to the building. The shear lag effect must therefore be accurately analyzed by considering these factors. This paper attempts to study the effect of torsional wind loads on the shear lag effect. Four wind load cases are adopted from American code (ASCE 7-22) to analyze the wind load effects on a 40-storied RCC tubular building. The results indicate that axial force distribution changes significantly with changes in the loading patterns of the building. Torsion and non-torsional load cases exhibit different unsymmetrical axial force distributions. Load cases with both direction loadings show notable differences in the axial force distribution compared to single-direction loadings. Axial force distributions due to the case of both face loading are unsymmetrical on both sides of the central column.

This paper presents the details of the wind tunnel investigations carried out on the aeroelastic behaviour of a tall RC chimney in the presence of surrounding structures for two typical power plant layouts in India. The RC chimney under investigation considered as a principal chimney has uniform diameter of 10.41 m and height of 124.5 m. The surrounding structures include 275 m tall chimney considered as interfering chimney and other power plant structures with the c/c distance-to-diameter ratio of 16 (layout-1) and 25 (layout-2) between principal chimney and interfering chimney. Experiments were conducted on the models with a geometric scale of 1:250 under simulated boundary layer conditions in the wind tunnel facility at CSIR-SERC, Chennai. Both the layouts are tested for various wind incidence angles and reduced velocity (\(\overline{U }/{n}_{0}D\)) ranges from 1.8 to 6.56. From the previous research works carried out, the magnification factor was observed to be maximum when the principal chimney is in downstream and interfering chimney is at 0° ± 15°. In this work, the maximum magnification factor was noticed to occur when the interfering chimney is at 15°, 180°, 210° for layout-1 and 35°, 65°, 320° for layout-2. In addition to the magnification factor, the variation of maximum interference factor for the resultant bending moment at critical wind speed with respect to the angle wind incidence was also discussed.

Physical simulation of atmospheric boundary layer characteristics is very important for wind tunnel testing of models on buildings and structures. A 1:300 scale flow simulation under open terrain conditions was conducted satisfactorily, in the recently established state-of-the-art boundary layer wind tunnel at JUET Guna, Madhya Pradesh, India. The size of the test section is 3.5 m (W) × 3.0 m (H) × 22 m (L). Using a combination of a trip board and floor roughness cubes, profiles of mean velocity, turbulence intensity and spectrum of wind speed were measured and compared with values recommended in the literature, including IS code and ESDU guidelines. The power law coefficient of the mean velocity was 0.16 and the value of turbulence intensity at 600 mm model height was 0.11. The measured spectra of wind speeds at different heights in model showed a good comparison with von Karman power spectrum to a scale of 1:300.