Experimental measurements of the drag force and the near-wake flow patterns of a longitudinally grooved cylinder. Issue 145 (October 2015)

• Record Type: Journal Article
• Authors: Zhou, Bo; Wang, Xikun; Guo, Wei; Zheng, Jiaxin; Tan, Soon Keat
• Is Part Of: Journal of wind engineering and industrial aerodynamics. Issue 145(2015)
• Page Start: 30
• Page End: 41
• Publication Date: 2015-10
• Subjects: Drag coefficient -- Drag reduction -- Grooved cylinder -- PIV; Wind-pressure -- Periodicals; Buildings -- Aerodynamics -- Periodicals; Pression du vent -- Périodiques; Constructions -- Aérodynamique -- Périodiques; Buildings -- Aerodynamics; Wind-pressure; Periodicals
• DOI: 10.1016/j.jweia.2015.05.013
• Languages: English
• ISSNs: 0167-6105

Abstract

Abstract: Flow around a smooth cylinder and a longitudinally grooved cylinder was investigated experimentally at Reynolds numbers ranged from 7.4×10 3 to 1.8×10 4 . This study aims to establish a better understanding of the effects of grooved surface on the drag coefficient and flow characteristics of the cylinder. The force measurement results showed that grooved surface significantly reduces the mean drag coefficient, say about 20% with reference to that of the smooth cylinder at the same Reynolds number. Distributions of the ensemble-averaged mean velocities, turbulent kinetic energy, Reynolds normal and shear stresses were obtained by using the particle image velocimetry (PIV) technique. The PIV measurement results showed that the shear layers emanated from the grooved cylinder are relatively lower in magnitude and smaller in size as compared to those from a smooth cylinder. Vortex shedding from the cylinder is weakened due to the presence of grooved surface. Highlights: Force and PIV measurements on a cylinder with longitudinal grooves are presented. Grooved surface is effective in reducing the mean drag on the cylinder. Grooved surface can mitigate the strength of vortex shedding from the cylinder. The grooved cylinder has a smaller wake with reduced magnitude of turbulent stresses.