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Article
Publication date: 29 December 2017

Siamak Nazemi, Ramin Khajavi, Hamidreza Rabie Far, Mohammad Esmail Yazdanshenas and Manouchehr Raad

During 2008 Olympics, Michael Phelps had a record-breaking performance. One contributing factor to his success was the full-body swimsuit he was wearing. Cases like these…

Abstract

Purpose

During 2008 Olympics, Michael Phelps had a record-breaking performance. One contributing factor to his success was the full-body swimsuit he was wearing. Cases like these were the reason for the initiation of study and research for improvement in the new generation of sport gears. The purpose of this paper is to show that drag force plays a significant role in swimmers’ speed through the water; thus, using swimsuit with minimized drag force becomes imperative for Olympians like Michael Phelps.

Design/methodology/approach

This paper shows a comparative evaluation of hydrodynamics of three PET fabrics with different finishings that have hydrophobic behavior over a range of Reynolds number 1.0218×103 and 1.365×103 in the air medium at 20°C ambient temperature, and Reynolds number ranging from 15.68856×103 to 20.958×103 in the water medium at 20°C ambient temperature under stable stretch conditions.

Findings

The results show that hydrophobic finishing reduces the drag force by 1.5 percent at the angles of attack of 0 and 90 degrees.

Originality/value

If all the factors are considered to be stable for the swimmer, the drag force reduces by 1.5 percent, thereby increasing the speed of swimmer by 1.22 percent, which means that the record of the swimmer improves by 0.819 seconds.

Details

International Journal of Clothing Science and Technology, vol. 30 no. 1
Type: Research Article
ISSN: 0955-6222

Keywords

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Article
Publication date: 18 July 2018

Siamak Nazemi, Ramin Khajavi, Hamidreza Rabie Far, Mohammad Esmail Yazdanshenas and Manouchehr Raad

This paper is based on the simulation of wind tunnel experiment for better understanding and predicting the behavior of PET fabric in the wind tunnel. This software…

Abstract

Purpose

This paper is based on the simulation of wind tunnel experiment for better understanding and predicting the behavior of PET fabric in the wind tunnel. This software calculates the drag force of fabric, illustrates pressure in the surrounding of airfoil and velocity of wind in the tunnel during different angles of attack (0°, 45° and 90°). The paper aims to discuss these issues.

Design/methodology/approach

The sol-gel method was applied for the synthesis of silica nano particles. So, PET fabric was coated with precursor (Tetra ethyl ortho silicate) solution first and the process continued on PET fabric. The morphology of obtained hydrophobic fabric samples and their surface roughness was observed and determined by atomic microscopes (AFM and SEM). Experimental data were used for simulation and modeling, and then results were interpreted.

Findings

It was concluded that the surface roughness and its amount can play a significant role in the drag reduction of PET fabric, and surface roughness can change the boundary layer from laminar to turbulent.

Originality/value

At 45 degrees angle of attack, larger boundary layer separation results in a large increase in the drag force. This model is useful for predicting flow behavior in the experimental wind tunnel.

Details

International Journal of Clothing Science and Technology, vol. 30 no. 3
Type: Research Article
ISSN: 0955-6222

Keywords

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