Aerodynamic behaviour of stretchable sports fabrics

Abstract

The variable surface characteristics of sports fabrics can affect the aerodynamics of athletes. In speed sports, most sports garments are worn with reasonable stretches that alter the fabrics' surface morphology. However, no correlation between the stretches and aerodynamic parameters is reported in the open literature. Therefore, the primary objective of this paper is to measure the aerodynamic properties of three commercially available sports fabrics over a range of Reynolds numbers and stretch conditions. Aerodynamic parameters of each fabric under a range of applied stretches were measured experimentally. The findings indicate that the surface morphology of the fabric under tension changes significantly and also affects the aerodynamic behaviour of the fabric. Less stretched knitted fabrics can provide an aerodynamic advantage by reducing drag at higher speeds, while more stretched knitted fabrics can provide an aerodynamic advantage by reducing drag at lower speeds. As the surface roughness increases, the critical Reynolds number (Recrit ) decreases and the minimum drag coefficient (C Dmin) value increases. Using same fabric under different tensions, the aerodynamic drag can be reduced up to 40% compared to a smooth-surface fabric.