Experimental Study on the Wake Characteristics of Composite Secondary Grooved Cylinder

• Published in: Water (Basel) Vol. 15; no. 11; p. 2073
• Main Authors: Liu, Liangqing, Luo, Xiaoyuan, Wang, Jianzheng, Shi, Zhisai, Yan, Fei
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 30.05.2023
• Subjects: Circular cylinders; Eddies; Energy; flow around the cylinder; Flow control; Flow velocity; Fluid flow; Force and energy; Gas pipelines; Investigations; Kinetic energy; Marine engineering; PIV; recirculation region; Reynolds number; Risers; secondary grooved; Shear stress; Underwater pipelines; Velocity gradient; Vortex generators; Vortex shedding; Vortices; wake; Water circulation
• ISSN: 2073-4441; 2073-4441
• DOI: 10.3390/w15112073

Flow around cylinders is widespread in marine engineering projects such as marine risers, marine pipelines, and tension leg. To understand the wake characteristics of the circular cylinder with different roughness, at a Reynolds number of 7400, a circulation water tunnel is used for experimental PIV measurements to compare the wake characteristics among the smooth cylinder, the original grooved cylinder, and the secondary grooved cylinder. The results revealed that the secondary grooved reduced the recirculation region, the flow-direction velocity gradient, the Reynolds shear stresses, and turbulent kinetic energy. Both small-scale and large-scale vortices are present in the wake vortex shedding. The instantaneous large-scale vortices behind the grooved cylinders are dispersed into several relatively small-scale vortices. Furthermore, the spike of the secondary grooved cylinder is a vortex generator, and directly impacts the generation of small eddies and the dissipation of large vortices.