Effect of a soccer ball’s seam geometry on its aerodynamics and trajectory

2019 ◽  
Vol 234 (1) ◽  
pp. 19-29 ◽  
Author(s):  
John Eric Goff ◽  
Sungchan Hong ◽  
Takeshi Asai
Keyword(s):  
Wind Tunnel ◽  
Computational Modeling ◽  
Critical Speed ◽  
Surface Design ◽  
Wind Tunnel Tests ◽  
Soccer Ball ◽  
Wind Tunnel Data ◽  
Linear Fit ◽  
Panel Surface ◽  
Lateral Deflections

Five different soccer balls, each possessing the traditional 32-panel surface design, were tested in a wind tunnel. Only seam depth and width varied between the balls. Wind-tunnel tests and an examination of correlation revealed that seam width with a linear fit [Formula: see text] and [Formula: see text] was a stronger indicator of a ball’s critical speed than seam depth. Wind-tunnel data were used for computational modeling of many soccer-ball trajectories. It was determined that variations in seam geometry resulted in fluctuations up to 4 m in the horizontal range of hard-hit, no-spin kicks that travel approximately 68 m. Those seam geometry variations also contributed to lateral deflections up to 4 m for the aforementioned hard-hit, no-spin kicks.

Optimisation of a Sailing Rig using Wind Tunnel Data

1997 ◽  
Author(s):  
IMC Campbell
Keyword(s):  
United States ◽  
Wind Tunnel ◽  
Research Programme ◽  
The United States ◽  
Wind Tunnel Tests ◽  
Aerodynamic Model ◽  
Analysis Methods ◽  
Wind Tunnel Data ◽  
Made In

A number of wind tunnel tests have been conducted by the Wolfson Unit in aid of the development of sailing rigs for both cruising and racing boats, including recent tests for the United States Sailing Association as part of the joint IMS/PHRF research programme. In the process of these tests developments have been made in both the test techniques and the analysis methods, which have enabled the components of drag to be identified for different sail settings. This paper describes the tests for evaluating the upwind rig performance of a sloop and compares the components of drag with those in the aerodynamic model used in the IMS VPP. The aerodynamic behaviour of the rig is described using plots of the variation of sail forces and moments with sail settings with the aim of helping sailors understand the effects of changing sail settings. It is shown that the wind tunnel data match closely the IMS aerodynamic model and that this model can be simply programmed by sailors and designers into a spreadsheet to enable the rig planform to be optimised for particular conditions. The results are compared with those obtained using a full VPP calculation.

Notes on the Opening Behaviour and the Opening Forces of Parachutes

1949 ◽  
Vol 53 (467) ◽  
pp. 1053-1062 ◽  
Author(s):  
F. O'Hara
Keyword(s):  
Wind Tunnel ◽  
Simple Form ◽  
Critical Speed ◽  
Air Flow ◽  
Line Length ◽  
Approximate Theory ◽  
Wind Tunnel Tests ◽  
Canopy Development ◽  
Critical Opening ◽  
Parachute System

SummaryAn approximate theory of parachute opening is suggested. A formula is derived for the critical opening speed (the highest speed at which the canopy develops fully) which indicates variation of the critical speed with fabric porosity, rigging line length and so forth, of the order observed in wind tunnel tests. Assuming a simple form for the air flow about the parachute, a formula is obtained also for the rate of opening of a canopy. This enables an analysis to be made of the motion of a store-parachute system during canopy development. The theory confirms the possibility of a large increase with altitude, found experimentally, in the maximum parachute force on the store.

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.

Comparison of free-flight and wind tunnel data for a generic fighterconfiguration

1982 ◽  
Author(s):  
G. WINCHENBACH ◽  
R. CHELEKIS ◽  
B. USELTON ◽  
W. HATHAWAY
Keyword(s):  
Wind Tunnel ◽  
Free Flight ◽  
Wind Tunnel Data

scholarly journals An overview of X-38 Hypersonic Wind Tunnel data and comparison with numerical results

1997 ◽  
Author(s):  
Charles Campbell ◽  
Jose Caram ◽  
Scott Berry ◽  
Michael DiFulvio ◽  
Tom Horvath ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Numerical Results ◽  
Hypersonic Wind Tunnel ◽  
Wind Tunnel Data
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