Abstract
The three-dimensional Large Eddy Simulation (LES) method is conducted to investigate the flow
characteristics around the square cylinder under a Reynolds number of Re = 2000. The considered corner
chamfered ratio C/D ranges from 0% to 50% with an interval of 5%, where C is the chamfered corner
dimension and D is the cylinder width. The focus is given on how C/D influences the flow structure, wake
recirculation region, flow separation bubbles, Strouhal number and aerodynamic forces of the cylinder. The
numerical results indicate that with increasing C/D, the mean drag coefficient, fluctuating lift coefficient,
mean pressure coefficient and fluctuating pressure coefficient decrease. Concurrently, the Strouhal number
exhibits an initial increase followed by a decrease with a rise in C/D. Significant changes in the recirculation
length and wake width are observed within 0%≤C/D≤50%. The introduction of corner chamfers induces
wall-attached evolution of the separated shear layers and suppresses three-dimensional instabilities,
significantly attenuating the pressure fluctuating on the surfaces, thereby reducing both mean drag and
fluctuating lift coefficients. As the chamfered ratio increases, the wake topology undergoes a transition from
disordered fragmented structures to spanwise highly coherent periodic vortices, leading to a narrowband
spectral transformation of the power spectra density. Finally, the mathematical relationships between the
corner chamfered ratio and the aerodynamic force coefficients and Strouhal number are established.
Key Words
Aerodynamic characteristics; Chamfered corner; Flow fields; Large eddy simulation; Square
cylinder
Address
Hongmiao Jing:1)School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
2)State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,
Shijiazhuang Tiedao University, Shijiazhuang 050043, China
3)Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province,
Shijiazhuang 050043, China
Pengcheng Xu:School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
Peng Guo:China Railway Construction Bridge Engineering Bureau Group Co., LTD., Tianjin 300300, China
Shuaichao Cui:China Railway Construction Bridge Engineering Bureau Group Co., LTD., Tianjin 300300, China
Yinping MA:School of Civil Engineering, Chongqing University, Chongqing 400045, China
Yunfei Zheng:Department of Railway Engineering, Shijiazhuang Institute of Railway Technology,
Shijiazhuang, 050041, China
Yi Su:School of Civil Engineering, Chongqing University, Chongqing 400045, China
Xiongwei Yang:School of Urban Geology and Engineering, Hebei GEO University, Shijiazhuang 050031, China
Qingkuan Liu:1)School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
2)State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,
Shijiazhuang Tiedao University, Shijiazhuang 050043, China
3)Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province,
Shijiazhuang 050043, China
Abstract
Explicitly resolving fine-scale turbulent motions is increasingly prioritized within the Weather Research
and Forecasting - Large-Eddy Simulation (WRF-LES) framework. While much is known about turbulence models
and grid resolution in flat terrain, few studies have evaluated WRF-LES 's performance in resolving separated turbulent
flow past obstacles. This study focuses on flows past a three-dimensional axisymmetric hill, examining the effects of
advection schemes (3rd to 6th order accuracy) and stabilization filters on simulation accuracy and efficiency. These
aspects are often overlooked in WRF-LES practices. We also explore the performance of advection schemes under
varying wind speeds and Smagorinsky coefficients. Results indicate that fundamental coherent structures are
reproduced in the wake of the hill, regardless of the advection scheme. Switching from odd-order to even-order
schemes significantly improve predictions of flow instability and small-scale turbulent motions. Energy spectra show
that even-order schemes better capture the turbulence inertial subrange, achieving nearly twice the effective resolution.
The study finds that numerical dissipation in odd-order schemes diminishes at lower wind speeds. Increasing the off
centering coefficient enhances numerical stability without significantly affecting flow separation or small-scale
turbulence generation.
Key Words
3D hill; advection scheme; large-eddy simulation; weather research and forecasting model
Address
Yong Cao:1)State Key Laboratory of Ocean Engineering, School of Ocean and Civil Engineering,
Shanghai Jiao Tong University, Shanghai, 200240, China
2)Chongqing Research Institute, Shanghai Jiao Tong University, Chongqing, 401135, China
3)Shenzhen Research Institute, Shanghai Jiao Tong University, Shenzhen 518063, China
Tao Tao:Engineering Research Center of Anhui Green Building and Digital Construction,
Anhui Polytechnic University, Wuhu, 241000, China
Shuyang Cao:5State Key Lab for Disaster Reduction in Civil Engineering, Tongji University, Shanghai, 200092, China
Kai Zhang:State Key Laboratory of Ocean Engineering, School of Ocean and Civil Engineering,
Shanghai Jiao Tong University, Shanghai, 200240, China
Dai Zhou:State Key Laboratory of Ocean Engineering, School of Ocean and Civil Engineering,
Shanghai Jiao Tong University, Shanghai, 200240, China
Abstract
In the current study, the effect of wind interference on a principal building caused by the presence of a
centrally located interfering building is investigated through experiments conducted in a boundary layer wind tunnel.
The distance between the interfering building and the principal building is gradually changed for five different
interfering building heights. Principal and interfering buildings have the same rectangular cross-section with an aspect
ratio of 1:3. Force and pressure measurements are undertaken independently. For validation, the outcomes of the two
measurements are compared with one another and with the Indian Standards. Results of force measurement are
presented in terms of wind interference factors for different parameters, while results for pressure measurement are
expressed in terms of mean and RMS wind pressure coefficients (𝐶𝑃 and 𝐶𝑃'). The highest along-wind force reduction
is noted to be 55.15% under wind interference conditions compared to that under the stand-alone condition, according
to the force measurement results. The force measurement results are appropriately and clearly explained by the contour
plots for the mean coefficients of wind pressure. Also, it is seen that the suctions observed on the leeward and the side
faces are higher for lower height interfering buildings. The highest 𝐶𝑃 value noted is 38.16% higher than that observed
for the stand-alone condition. Probability density functions plotted for critical pressure points at different spacings
reveal that 𝐶𝑃 values on the side face reach closer to stand-alone condition faster compared to that on the windward
and leeward faces.
Address
Bharat S. Chauhan:1)Heritage and Special Structures Group, CSIR- Central Building Research Institute,
Roorkee, Uttarakhand - 247667, India
2)Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
Anupam Chakrabarti:Department of Civil Engineering, Indian Institute of Technology Roorkee,
Roorkee, Uttarakhand - 247667, India
Ashok K. Ahuja:Department of Civil Engineering, Indian Institute of Technology Roorkee,
Roorkee, Uttarakhand - 247667, India
Adal Mengesha Yimer:Department of Civil Engineering, Debre Tabor University, Ethiopia
Abstract
Short-term wind speed forecasting is critical for dynamic line rating (DLR) to maximize grid capacity,
yet existing methods face challenges in handling nonlinearity and stochasticity. We propose a novel hybrid model
integrating Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN),
ARIMA, and LSTM, with three key contributions: (1) An enhanced ICEEMDAN algorithm reducing residual noise
energy by 5-8% and mode mixing by 31% compared to CEEMDAN; (2) A frequency-aware modeling strategy that
dynamically assigns linear (ARIMA) and nonlinear (LSTM) sub-models based on Hurst exponent analysis; (3) A
GPU-accelerated implementation achieving real-time prediction with 28-second latency. Validated on China's
transmission corridors, the model reduces RMSE by 65.2% over standalone LSTM and increases line ampacity by
21.2% compared to static ratings. Its robustness (99.2% availability during typhoons) and computational efficiency
(150 x faster than conventional systems) demonstrate significant potential for smart grid applications.
Key Words
dynamic line rating; empirical mode decomposition; hybrid model; real-time forecasting; wind
speed prediction
Address
Feng Yang:College of Energy and Mechanical Engineering, Shanghai University of Electric Power,
Shanghai 201306, China
Xiao Qin:College of Energy and Mechanical Engineering, Shanghai University of Electric Power,
Shanghai 201306, China
Zhengkang Li:College of Energy and Mechanical Engineering, Shanghai University of Electric Power,
Shanghai 201306, China
Kai Ji:College of Energy and Mechanical Engineering, Shanghai University of Electric Power,
Shanghai 201306, China
Abstract
Downburst outflows interacting with uplifted terrain features, such as escarpments, can substantially
accelerate local near-ground wind speeds and thereby aggravate wind hazards. However, existing downburst
research has predominantly focused on wind-field characteristics over flat and smooth terrains, whereas the effects of
elevated terrains remain insufficiently understood. To address this gap, the present study conducts an experimental
investigation into how escarpment terrain modifies the mean and fluctuating components of downburst-like wind
velocity profiles. A downburst-like flow was reproduced using a plane wall-jet facility, and the influences of
escarpment slope angle and the upstream (pre-escarpment) surface roughness were systematically examined. The
results show that the escarpment terrain significantly impacts the mean and fluctuating wind profiles of the
downburst at the escarpment top-position, and the wind profile no longer maintains the "nose" shape, compared to
that from the flat ground. Moreover, the escarpment has an apparent obstructive effect on the mean speed profile of
the downburst-like wind, showing a deceleration effect at the escarpment toe-position, exhibiting wind speed
characteristics similar to those of the flat ground in the mid-escarpment area, and presenting a significant speed-up
effect at the escarpment top-position. Meanwhile, the influence of the escarpment on the speed-up ratio at the
escarpment top is mainly concentrated in the near-wall region, with the maximum value reaching 1.5. The influence
of the roughness area is mainly occurring on the outer layer of the downburst-like flow, and the roughness area
significantly impacts the wind speed-up ratio along the entire wind profile.
Key Words
downburst-like flow; escarpment terrain; mean wind speed; speed-up ratio; turbulence
intensity; wind tunnel test
Address
Yongli Zhong:1)School of Civil and Hydraulic Engineering, Chongqing University of Science and Technology,
Chongqing 401331, China
2)Chongqing Key Laboratory of Disaster Prevention and Reduction in Power Transmission Engineering,
Chongqing University of Science and Technology, Chongqing 401331, China
3)Wind Engineering and Aerodynamics Research Center, Chongqing University of Science and Technology,
Chongqing, 401331, China
Qiyan Wu:School of Civil and Hydraulic Engineering, Chongqing University of Science and Technology,
Chongqing 401331, China
Xiangjun Tan:School of Civil and Hydraulic Engineering, Chongqing University of Science and Technology,
Chongqing 401331, China
Zhitao Yan:1)School of Civil and Hydraulic Engineering, Chongqing University of Science and Technology,
Chongqing 401331, China
2)Chongqing Key Laboratory of Disaster Prevention and Reduction in Power Transmission Engineering,
Chongqing University of Science and Technology, Chongqing 401331, China
3)Wind Engineering and Aerodynamics Research Center, Chongqing University of Science and Technology,
Chongqing, 401331, China
4)School of Civil Engineering, Chongqing University, Chongqing 400045, China
Wenshan Shan:School of Civil and Hydraulic Engineering, Chongqing University of Science and Technology,
Chongqing 401331, China
Zulin Huang:1)School of Civil and Hydraulic Engineering, Chongqing University of Science and Technology,
Chongqing 401331, China
2)Chongqing Key Laboratory of Disaster Prevention and Reduction in Power Transmission Engineering,
Chongqing University of Science and Technology, Chongqing 401331, China
