A Study of Aerodynamic Drag of Contemporary Footballs

AbstractMost modern footballs possess varied surface characteristics which can affect the flight trajectory of the football. Although the aerodynamic behavior of other sports balls have been studied well, little information is available about the aerodynamic behavior of newly introduced footballs with varied seam configurations and number of panels. Therefore, the primary objective of this study is to understand the surface characteristics mainly the seam depth and seam height and their effects on aerodynamic of a range of new generation balls. Four new generation footballs: Kapanya, Cafusa, Tango and Brazuca were selected for this study. Seam length and depth of seam for each ball were measured using 3D scanning technology and also manual measurement. Additionally, the aerodynamic drag forces were measured using wind tunnel over a range of wind speeds for two positions of each ball. It was found that the seam length and depth of seam have influence on the aerodynamic drag of these modern footballs. Results also indicate that the sideway variation of aerodynamic drag is minimal for the Brazuca ball. As a result, this ball may have better stability in flight. The lowest aerodynamic drag was found for the Cafusa ball at high speeds which indicates that this ball is suitable for long distance pass. However, it has highest sideway drag variation that may cause instability in flight

Flight trajectory simulation of badminton shuttlecocks

Abstract The aerodynamic behavior of badminton shuttlecocks differs considerably from other ball, racket or projectile sports. Being a bluff body, the shuttlecock generates high aerodynamic drag and steep flight trajectory. Despite the popularity of the badminton game, scant information is available in the public domain about shuttlecock aerodynamics and its flight trajectory. The primary objective of this work was to construct the flight trajectory of a synthetic and feather shuttlecocks for a range of wind speeds under non-spinning condition based on aerodynamic data obtained experimentally

Indigenous and imported natural gas and the economic growth of Bangladesh: The challenges ahead

Chowdhury, MH ORCiD: 0000-0003-3859-3860The global consumption of natural gas is expected to increase at an average of 1.6% over the next 5 years from 3.7 trillion cubic meter (tcm) used in 2017. Although the current use of gas in power generation is dominant followed by industry, residential and other sectors during 2011-2017, the global industry is expected to be the main driver for gas consumption followed by power generation, residential and commercial and other sectors by 2023. Many countries including Bangladesh use natural gas primarily for power generation. Among the main reason was energy security, availability of smooth supply of own relatively cheaper natural gas. As the demand for power has increased and the country could not extract indigenous discovered coal due to complex mine water management and agricultural land rehabilitation, its indigenous fuel supply restricted utilizing installed capacity of power generation, impeding industrial growth and development. This paper reviews the status of natural gas in Bangladesh and the engagements of local and international oil companies in natural gas exploration. The paper highlights the need for transboundary gas importation and associated infrastructure to support its development activities. It is recommended that the indigenous and transboundary gas to be managed efficiently and a long-term strategy for sustained supply of fuel from multiple sources to be formulated to maximise the energy security and achieving Bangladesh Vision 2041. © 2019 The Authors. Published by Elsevier Ltd

A review on the regional collaboration of power utilisation in South Asia

Chowdhury, MH ORCiD: 0000-0003-3859-3860Economic prosperity and development in South Asia are significantly restricted by the insufficient power supply. Inadequate indigenous energy resource of each South Asian nation is not enough to generate power for meeting the growing demand. Moreover, the availability of limited indigenous energy resources differs from one country to another in South Asia. In addition to availability variation of indigenous energy sources, the climate conditions also vary resulting in variable power demand and power generation capacity. This paper reviews the current power generation capacity of all eight nations of South Asia. It highlights the bilateral and multilateral collaboration opportunities in power generation and the need for cross boarder power trade among South Asian nations. The review emphasises that the bilateral and multi-lateral cooperation will allow overcoming regional power shortage and augmenting collective energy security, economic and political integration. © 2019 The Authors. Published by Elsevier Ltd

The compression effect on aerodynamic properties of sports fabrics

Generally, the surface textures of the sport fabrics influence the aerodynamic properties of the athletes in motion. On the other hand, the surface texture of sports garments largely depends on the applied stress while wearing. Therefore, the fitting of garments on athlete bodies can make the aerodynamic behaviour more complex. Additionally, the fabric at an appropriate level of stretching can provide an aerodynamic advantage. The primary objective of this study was to measure the aerodynamic properties of three commercially available sport fabrics using a standard cylinder methodology over a range of Reynolds numbers and stretch conditions alone with microscopic analysis. The results indicated that the surface texture of the fabric was changed under different stretched levels and these changes in the surface texture had a notable effect on the aerodynamic drag. The surface texture of fabrics caused transitional effect at lower speeds compared to the smooth bare cylinder providing almost 30% drag reduction