scholarly journals Wind Tunnel Tests of Wind-Induced Snow Distribution for Cubes with Holes

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xintong Jiang ◽  
Zhixiang Yin ◽  
Hanbo Cui
Keyword(s):  
Wind Tunnel ◽  
Snow Depth ◽  
Structural Safety ◽  
Windward Side ◽  
Leeward Side ◽  
Wind Tunnel Tests ◽  
Maximum Snow Depth ◽  
Adjacent Structures ◽  
Significant Difference ◽  
Snow Distribution

The nonuniform distribution of snow around structures with holes is extremely unfavorable for structural safety, and the mechanism of wind-snow interaction between adjacent structures with holes needs to be explored. Therefore, a wind tunnel simulation was performed, in which quartz particles with an average particle size of 0.14 mm as snow particles were used, and cubes with dimensions of 100 mm × 100 mm × 100 mm each containing a hole with the size of 20 mm × 20 mm were employed as structures. Firstly, the quality of a small low-speed wind tunnel flow field was tested, and then the effects of hole orientation (hole located on the windward side, leeward side, and other vertical sides) and absence of holes on the surface of a single cube were studied. Furthermore, the effects of different hole locations (respectant position, opposite position, and dislocation) and relative spacing (50 mm, 100 mm, and 150 mm) on the surfaces of two cubes and the snow distribution around them were investigated. It was concluded that the presence and location of hole had a great influence on snow distribution around cubes. Snow distribution was favorable when hole was located on the other vertical sides of the test specimen. The most unfavorable snow distribution was obtained when the holes on the two-holed sides of the cubes were respectant with a maximum snow depth coefficient of 1.4. A significant difference was observed in the snow depths of two sides of cubes when holes were dislocated. When two holes were respectant, surrounding snow depth was decreased, and the maximum snow depth on model surface area was increased with the increase of spacing. Wind tunnel tests on holed cubes provided a reference for the prediction of snow load distribution of typical structures with holes.

The Numerical Simulation of the Impact on the Hangzhou Bay Bridge Offshore Platform and the Sightseeing Tower

2012 ◽  
Vol 532-533 ◽  
pp. 352-356
Author(s):  
Hua Bai ◽  
Fang Liang Wang ◽  
Yu Li
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Surface Pressure ◽  
Wind Tunnel Test ◽  
Offshore Platform ◽  
Wind Pressure ◽  
Windward Side ◽  
Hangzhou Bay ◽  
Leeward Side ◽  
The Impact

In this paper, the distribution of surface wind pressure and wind speed of Hangzhou bay bridge, offshore platform and sightseeing tower is numerically simulated based on Fluent. Two turbulence models, standard k ε model and Realizable k ε model, are used. The influence of the wind pressure distribution of the offshore platform and sightseeing tower by Hangzhou bay bridge is also analyzed. And the detailed comparison between numerical simulation and wind tunnel test is given. Results show that the impact of Hangzhou bay bridge on platform and sightseeing tower occurs mainly with the angle of the wind less than 450. When the angle of the wind is more than 450, the impact is little. The upper of the sightseeing tower does not almost suffer the effect of other buildings. The surface pressure of the platform changes from 5% to 15% between under bridge and under non-bridge condition. The surface pressure of sightseeing tower changes from 0.05% to 3%. The influence on the platform by the bridge is significant but not significant on the sightseeing tower. The simulation results of the tower and mast structure given by both standard k ε model and Realizable k ε model find that the windward side is ideal; the crosswind side is the best; the leeward side is less than ideal. By contrast, the Realizable k ε model is a closer correlation with wind tunnel test than standard k ε model.

scholarly journals Research on Snow Load Characteristics on a Complex Long-Span Roof Based on Snow–Wind Tunnel Tests

2019 ◽  
Vol 9 (20) ◽  
pp. 4369 ◽  
Author(s):  
Guolong Zhang ◽  
Qingwen Zhang ◽  
Feng Fan ◽  
Shizhao Shen
Keyword(s):  
Wind Tunnel ◽  
Basic Characteristic ◽  
Wind Tunnel Test ◽  
Experimental System ◽  
Similarity Criteria ◽  
Wind Tunnel Tests ◽  
Snow Load ◽  
Long Span ◽  
Characteristic Modes ◽  
Snow Distribution

A considerable number of studies have been carried out for predicting snowdrifts on roofs over the years. However, few studies have focused on snowdrifts on complex long-span roofs, as the complex shape and fine structure pose significant challenges. In this study, to simplify the calculation requirements of snow load on such roofs, work was conducted to decompose the snowdrift on a complex roof into snowdrifts on several simple roofs. First, the snow–wind tunnel test similarity criteria were investigated based on a combined air–snow–wind experimental system. Thereafter, with reference to the validated experimental similarity criteria, a series of snow–wind tunnel tests were performed for snowdrifts on a complex long-span structure under the conditions of different inflow directions. Finally, based on empirical orthogonal function (EOF) analysis, the snowdrifts on the complex roof were decomposed into basic characteristic distribution modes, including snowdrifts caused by the local and overall roof forms. The snow distribution under a specific inflow direction could be derived from the weighted combination of the basic characteristic modes, based on the wind direction coefficients. Therefore, it is possible for the snow load on a complex roof to be estimated preliminarily based on the snow distributions on several simple roofs.

Vortex-induced vibration of a truss girder with high vertical stabilizers

2018 ◽  
Vol 22 (4) ◽  
pp. 948-959 ◽  
Author(s):  
Haojun Tang ◽  
KM Shum ◽  
Qiyu Tao ◽  
Jinsong Jiang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Vortex Shedding ◽  
Windward Side ◽  
Induced Response ◽  
Vortex Induced Vibration ◽  
Wind Tunnel Tests ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

To improve the flutter stability of a long-span suspension bridge with steel truss stiffening girder, two vertical stabilizers of which the total height reaches to approximately 2.9 m were planned to install on the deck. As the optimized girder presents the characteristics of a bluff body more, its vortex-induced vibration needs to be studied in detail. In this article, computational fluid dynamics simulations and wind tunnel tests are carried out. The vortex-shedding performance of the optimized girder is analyzed and the corresponding aerodynamic mechanism is discussed. Then, the static aerodynamic coefficients and the dynamic vortex-induced response of the bridge are tested by sectional models. The results show that the vertical stabilizers could make the incoming flow separate and induce strong vortex-shedding behind them, but this effect is weakened by the chord member on the windward side of the lower stabilizer. As the vortex-shedding performance of the optimized girder is mainly affected by truss members whose position relationships change along the bridge span, the vortex shed from the girder can hardly have a uniform frequency so the possibility of vortex-induced vibration of the bridge is low. The data obtained by wind tunnel tests verify the results by computational fluid dynamics simulations.

scholarly journals Experimental Study of Interference Effects of a High-Rise Building on the Snow Load on a Low-Rise Building with a Flat Roof

2021 ◽  
Vol 11 (23) ◽  
pp. 11163
Author(s):  
Qingwen Zhang ◽  
Yu Zhang ◽  
Ziang Yin ◽  
Guolong Zhang ◽  
Huamei Mo ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Snow Accumulation ◽  
Interference Effects ◽  
Wind Tunnel Tests ◽  
Snow Load ◽  
Building Roof ◽  
High Rise ◽  
High Rise Building ◽  
Snow Distribution ◽  
Flat Roof

To explore the interference effects of a high-rise building on the snow load on a low-rise building with a flat roof, a series of wind tunnel tests were carried out with fine silica sand as a substitute for snow particles. The effects of the height of the interfering building and the distance between buildings on the snow distribution of the target building under three different wind directions were studied. The snow depth on the target building roof and the mass of particles blown off from the target building were measured during the wind tunnel tests, and the results showed that the snow distribution of the target building roof tends to be uniform when the interfering building is located upstream of the target building due to the shelter effect. When the interfering building is on the side of the target building, the snow distribution of the target building tends to be more uneven, because the interfering building increases the friction velocity on the target building roof near the interfering building. However, when the interfering building is located downstream of the target building, there will be an amplification effect of snow accumulation, and the snow distribution on the target building roof is nearly the same as that of the isolated condition. Under each wind direction, the interference effect of the snow load increases with the increase of the building height and the decrease of the building spacing. Therefore, the influence of the surrounding buildings on the snow distribution of the building roof cannot be ignored and should be considered in the structure design.

Analysis of anemotropism in the mushroom Psilocybe cubensis

1984 ◽  
Vol 62 (2) ◽  
pp. 296-300 ◽  
Author(s):  
Edmond R. Badham ◽  
Dwight T. Kincaid
Keyword(s):  
Growth Factor ◽  
Wind Tunnel ◽  
Environmental Factors ◽  
Water Loss ◽  
Air Flow ◽  
Turgor Pressure ◽  
Windward Side ◽  
Leeward Side ◽  
Controlled Conditions ◽  
Lines Of Evidence

The bending of the growing basidiocarp of Psilocybe cubensis into air flow (anemotropism) was investigated. Basidiocarps were placed in a wind tunnel under controlled conditions and anemotropism was evaluated in relation to the physical dimensions of the mushroom and to certain environmental factors. Six lines of evidence are presented demonstrating that the cause of the bending is a greater water loss from the windward side than from the leeward side of the mushroom. Dehydration may result in unequal growth owing to differential production or activity of a hypothetical growth factor or because of a differential in turgor pressure.

scholarly journals Wind Tunnel Tests and Numerical Simulations of Wind-Induced Snow Drift in an Open Stadium and Gymnasium

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xintong Jiang ◽  
Zhixiang Yin ◽  
Hanbo Cui
Keyword(s):  
Wind Tunnel ◽  
Numerical Simulations ◽  
Wind Direction ◽  
Interference Effect ◽  
Mutual Interference ◽  
Wind Tunnel Tests ◽  
Direction Angle ◽  
Long Span ◽  
Snow Drift ◽  
Snow Distribution

A long-span sports centre generally comprises multiple stadiums and gymnasiums, for which mutual interference effects of wind-induced snow motion are not explicitly included in the specifications of various countries. This problem is addressed herein by performing wind tunnel tests and numerical simulations to investigate the snow distribution and mutual interference effect on the roofs of long-span stadiums and gymnasiums. The wind tunnel tests were used to analyse the influences of the opening direction (0°, 90°, 180°, and 270°) and spacing (0.3 L, 0.5 L, 1 L, 1.5 L, 2 L, and 2.5 L, where L is the gymnasium span) of the stadium and gymnasium. The wind tunnel tests and numerical simulations were used to analyse the influence of the wind direction angle (from 0° to 315°, there are a total of eight groups in 45° intervals). The following results were obtained. The stadium opening had a significant effect on the snow distribution on the surface of the two structures. An even snow distribution was obtained when the stadium opened directly facing the gymnasium, which corresponded to the safest condition for the structures’ surfaces. As the spacing between the buildings increased, the interference effect between the two structures was reduced. The interference was negligible for a spacing of 2 L. The stadium had the most significant amplification interference effect on the gymnasium for a wind direction angle of 45°, which was extremely unfavourable to the safety of the structure. The most favourable wind direction angle was 270°, where there were both amplification interference and blockage interference.

scholarly journals Wind-Induced Phenomena in Long-Span Cable-Supported Bridges: A Comparative Review of Wind Tunnel Tests and Computational Fluid Dynamics Modelling

2021 ◽  
Vol 11 (4) ◽  
pp. 1642
Author(s):  
Yuxiang Zhang ◽  
Philip Cardiff ◽  
Jennifer Keenahan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Careful Analysis ◽  
Wind Effects ◽  
Wind Tunnel Tests ◽  
Long Span Bridges ◽  
Long Span ◽  
Comparative Review ◽  
Dynamics Modelling

Engineers, architects, planners and designers must carefully consider the effects of wind in their work. Due to their slender and flexible nature, long-span bridges can often experience vibrations due to the wind, and so the careful analysis of wind effects is paramount. Traditionally, wind tunnel tests have been the preferred method of conducting bridge wind analysis. In recent times, owing to improved computational power, computational fluid dynamics simulations are coming to the fore as viable means of analysing wind effects on bridges. The focus of this paper is on long-span cable-supported bridges. Wind issues in long-span cable-supported bridges can include flutter, vortex-induced vibrations and rain–wind-induced vibrations. This paper presents a state-of-the-art review of research on the use of wind tunnel tests and computational fluid dynamics modelling of these wind issues on long-span bridges.

Galloping vibration of stay cable installed with a rectangular lamp: Field observations and wind tunnel tests

2021 ◽  
Vol 215 ◽  
pp. 104685
Author(s):  
An Miao ◽  
Li Shouying ◽  
Liu Zhiwen ◽  
Yan Banfu ◽  
Li Longan ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Field Observations ◽  
Stay Cable ◽  
Wind Tunnel Tests

Wind tunnel tests and dynamic analysis of wind-induced response of a transmission tower on a hill

2021 ◽  
pp. 136943322110339
Author(s):  
Jian Guo ◽  
Changliang Xiao ◽  
Jiantao Li
Keyword(s):  
Wind Tunnel ◽  
Wind Field ◽  
Dynamic Responses ◽  
Interactive Effects ◽  
Induced Response ◽  
Transmission Tower ◽  
Structural Dynamic ◽  
Wind Tunnel Tests ◽  
Hill Slope ◽  
The Hill

A hill with a lattice transmission tower presents complex wind field characteristics. The commonly used computational fluid dynamics (CFD) simulations are difficult to analyze the wind resistance and dynamic responses of the transmission tower due to structural complexity. In this study, wind tunnel tests and numerical simulations are conducted to analyze the wind field of the hill and the dynamic responses of the transmission tower built on it. The hill models with different slopes are investigated by wind tunnel tests to measure the wind field characteristics, such as mean speed and turbulence intensity. The study shows that the existence of a transmission tower reduces the wind speed on the leeward slope significantly but has little effect on the windward slope. To study the dynamic behavior of the transmission tower, a hybrid analysis procedure is used by introducing the measured experimental wind information to the finite element tower model established using ANSYS. The effects of hill slope on the maximum displacement response of the tower are studied. The results show that the maximum value of the response is the largest when the hill slope is 25° compared to those when hill slope is 15° and 35°. The results extend the knowledge concerning wind tunnel tests on hills of different terrain and provide a comprehensive understanding of the interactive effects between the hill and existing transmission tower regarding to the wind field characteristics and structural dynamic responses.

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