Abstract
Turbulence integral lengthscale and lateral and vertical turbulence intensities are sometimes not measured
in wind tunnel experiments. The resulting uncertainty in inflow conditions cascades into uncertainties in the surface
pressure, drag and lift coefficients, and the wind response of tall buildings. This paper utilizes Large Eddy Simulation
(LES) with a divergence-free turbulence generator to investigate a set of five inflow conditions generated using
different assumptions related to building height and turbulence integral lengthscale, and the ratio between three
components of turbulence intensities. The effects of the inflow assumptions on the downstream incident flow, on the
surface pressure coefficient of a tall rectangular building of 1:4 width to height ratio, on drag and lift moment
coefficients are all evaluated. Furthermore, an example steel-frame-tube structure is considered to investigate the
effects of the inflow turbulence on its background, resonant and peak displacement response using modal analysis
with gust peak factors. It is observed that distinct turbulence inflow conditions tend to converge towards similar
statistical profiles downstream. However, within this envelope of convergence, a range of potential values persists,
indicating significant remaining uncertainty. The inflow turbulence integral lengthscale is found to have an effect up
to 13% on the peak along-wind response and 4% on the across-wind response. The lateral and vertical turbulence
intensity is found to have effects of up to 13% and 24% on the two peak responses, respectively. These results
highlight the importance of considering a range of inflow assumptions when conducting LES to reproduce and
interpret WT results.
Key Words
dynamic structural analysis; Large Eddy Simulation (LES); steel-frame-tube system; synthetic
turbulence generator; tall building
Address
Jack K. Wong:University of Toronto, 35 St. George St., Toronto, Ontario, Canada
Oya Mercan:University of Toronto, 35 St. George St., Toronto, Ontario, Canada
Paul J. Kushner:University of Toronto, 35 St. George St., Toronto, Ontario, Canada
Abstract
The aerodynamic behavior of vertical-axis wind turbines (VAWTs), particularly the H-type Darrieus
configuration, remains central to renewable energy research due to persistent challenges in self-starting and efficiency
at low tip speed ratios (TSRs). This study presents a numerical investigation of a modified NACA0018 aerofoil with
chordwise surface openings, termed a J-shaped aerofoil, operating under Darrieus motion. Two-dimensional CFD
simulations in ANSYS Fluent evaluated opening ratios of 30%, 60%, and 90% of chord length, focusing on lift, drag,
and chordwise force coefficients during dynamic stall. A validated oscillating aerofoil model with user-defined
pitching replicated Darrieus kinematics, with systematic variation of TSR and pitch angle. Results show that larger
openings enhance lift and delay stall onset in the positive angle of attack phase, improving self-starting potential.
However, these gains are offset by increased drag and reduced performance during the negative phase, particularly
downstream. The J-shaped aerofoil with 90% opening achieved ~30% higher peak lift than the conventional profile,
with improved flow reattachment and vortex dynamics observed. Despite elevated downstream losses, the enhanced
upstream torque indicates a net advantage for turbine start-up capability. These findings provide insight for
optimizing blade design in low-Reynolds-number VAWTs, balancing self-starting improvement against efficiency at
higher TSRs.
Address
Yunus Celik:1)Energy2050, Department of Mechanical Engineering, Faculty of Engineering, University of Sheffield,
Western Bank S10 2TN, Sheffield, United Kingdom
2)Department of Aeronautical Engineering, Sivas University of Science and Technology,
Gültepe Mahallesi 58000, Sivas, Turkey
Derek Ingham:Energy2050, Department of Mechanical Engineering, Faculty of Engineering, University of Sheffield,
Western Bank S10 2TN, Sheffield, United Kingdom
Lin Ma:Energy2050, Department of Mechanical Engineering, Faculty of Engineering, University of Sheffield,
Western Bank S10 2TN, Sheffield, United Kingdom
Burhan Necati Kiziloglu:Department of Aeronautical Engineering, Sivas University of Science and Technology,
Gültepe Mahallesi 58000, Sivas, Turkey
Mohamed Pourkashanian:Energy2050, Department of Mechanical Engineering, Faculty of Engineering, University of Sheffield,
Western Bank S10 2TN, Sheffield, United Kingdom
Abstract
This study investigates the aerodynamic force characteristics and flow field mechanisms of wide-width
double-box composite girders through integrated wind tunnel testing and numerical simulation. Initially,
aerodynamic analysis was conducted across eleven wind attack angles (-10° to +10° at 2° intervals) while
maintaining the prototype bridge aspect ratio of 12.8. Subsequently, parametric analysis was performed for horizontal
flow conditions (0°), examining six aspect ratios (9, 11, 12.8, 15, 17, and 19). The results demonstrate that, under the
aspect ratio of 12.8, as the wind attack angle varies from -10° to 10°, the drag coefficient and the absolute value of the
lift coefficient initially decreases and then increases, the direction of moment changes from counterclockwise to
clockwise. At 0° wind attack angle, as the aspect ratio increases, the drag coefficient remains constant initially and
then increases, the absolute value of the lift coefficient initially decreasing and then increasing, and the moment
coefficient gradually decreases. The lift and moment coefficients are smaller during the construction and service
stages. Calculation formulas for aerodynamic force coefficient with different aspect ratios under 0° wind attack angle
are presented, which can provide a reference for the wind load design of wide-width double-box composite girders in
practical engineering.
Key Words
aerodynamic force characteristics; flow field mechanism; numerical simulation; wide-width
double-box composite girders; wind tunnel testing
Xiaobing Liu:1)School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
2)Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province,
Shijiazhuang 050043, China
Dewang Zhang:School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
Luqian Ma:School of Traffic and Transportation, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
Qun Yang:1)School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
2)Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province,
Shijiazhuang 050043, China
Abstract
This study compares pressure distributions on non-structural components (doors, windows, soffits, and
fascia), due to hurricane winds from Wall of Wind (WoW) facility tests, field measurements on a residential house in
Satellite Beach, Florida, during Hurricane Nicole (2022), and computational fluid dynamics (CFD) simulations. WoW
testing was on a full-scale single-story building, equipped with wireless pressure sensors and Scanivalve patches. Wind
loads were measured in the field using the same sensor system. The CFD simulations reproduced wind tunnel flow
conditions. Measured pressure coefficients (𝐶𝑝) on the doors and windows (with and without shutters), soffits, and
fascia are compared against 𝐶𝑝 values under ASCE 7-22 provisions. Results indicate that the 𝐶𝑝 from field
measurements is localized and strongly dependent on wind direction in urban surroundings. Aluminium storm shutters
reduce positive 𝐶𝑝 values on doors and windows at some angles but do not affect negative values. Soffits exhibit the
highest 𝐶𝑝 values at their edges, while fascia experience lower 𝐶𝑝 values in comparison. The strongest suction forces
occur under the roof
Key Words
ASCE 7-22; CFD; components and cladding; field measurement; pressure sensor; wall-of-wind;
wireless sensor network system
Address
Jian Zhang:Department of Aerospace, Physics and Space Sciences, Florida Institute of Technology,
150W. University Blvd, Melbourne, FL 32901, USA
Chelakara S. Subramanian:Department of Aerospace, Physics and Space Sciences, Florida Institute of Technology,
150W. University Blvd, Melbourne, FL 32901, USA
Jean-Paul Pinelli:Department of Mechanical and Civil Engineering, Florida Institute of Technology,
150W. University Blvd, Melbourne, FL 32901, USA
Steven Lazarus:Department of Ocean Engineering and Marine Sciences, Florida Institute of Technology,
150W. University Blvd, Melbourne, FL 32901, USA
Hadley Besing:Department of Ocean Engineering and Marine Sciences, Florida Institute of Technology,
150W. University Blvd, Melbourne, FL 32901, USA
Diego Robles Cortes:Department of Aerospace, Physics and Space Sciences, Florida Institute of Technology,
150W. University Blvd, Melbourne, FL 32901, USA
Abstract
As for the wind resistance design for building structures on hilly terrains, the fundamental issue is to
establish the wind topographic acceleration effect. Since the hill slope plays an important role in the wind flow around
hilly terrains, its influence on the wind topographic acceleration effect needs further investigation. In this study, the
large eddy simulation (LES) was carried out to study the influence of slope variation on the wind topographic
acceleration effect around a three-dimensional hill. The results indicate that the hill slope significantly affects the
distribution of the wind topographic acceleration effect over the hill. The coverage of the wind topographic acceleration
effect increases with the slope increase. At the hill windward, the mean wind topographic acceleration effect is
suppressed with the increasing slope and reaches its maximum at the hilltop, while it shows the opposite for the
fluctuating counterpart. On the hill leeward, the mean wind topographic acceleration effect gradually reduces with the
increase of slope. Moreover, a critical slope of 25° for the fluctuating wind topographic acceleration effect can be found
near the hill surface on the leeward side. The fluctuating wind topographic reduces with the slope increase when α
25°, while exhibits an opposite trend when 25° > 25°. A mathematical model, which incorporates the slope, height and
topographic influence factors, was then proposed to depict the distribution of the mean and fluctuating wind
topographic acceleration effect coefficients. Compared to different national load codes, the proposed model presents a
good performance not only in predicting the mean wind topographic acceleration effect, but also in possessing the
capability in the prediction of the fluctuating wind topographic acceleration effect.
Key Words
Wind topographic acceleration effect; Large eddy simulation; Three-dimensional hill;
Mathematical model; Hill slopes
Address
Liang Li:School of Civil Engineering, Henan University of Technology, Zhengzhou 450001, China
Deqian Zheng:School of Civil Engineering, Henan University of Technology, Zhengzhou 450001, China
Guixiang Chen:School of Civil Engineering, Henan University of Technology, Zhengzhou 450001, China
Wenyong Ma:Wind Engineering Research Center, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
Pingzhi Fang:Asia-Pacific Typhoon Collaborative Research Center, Shanghai 201306, China
