Experimental study on flow past a circular cylinder with rough surface. (15th November 2015)

• Record Type: Journal Article
• Authors: Zhou, Bo; Wang, Xikun; Guo, Wei; Gho, Wie Min; Tan, Soon Keat
• Is Part Of: Ocean engineering. Volume 109 (2015)
• Page Start: 7
• Page End: 13
• Publication Date: 2015-11-15
• Subjects: Drag reduction -- Surface roughness -- Grooved cylinder -- Dimpled cylinder -- Particle Image Velocimetry (PIV); Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2015.08.062
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Flow past a circular cylinder with smooth, grooved and dimpled surface (roughness coefficient k / D =0.05, where k is the depth of the grooves/dimples and D is the outer diameter of the cylinder) was investigated in an open channel and a towing tank. Two different sizes of cylinder ( D =40 and 100 mm) were considered in the present study. The Reynolds numbers based on the cylinder diameter ranged from 7.4×10 3 to 8×10 4 . The fluid dynamic forces (drag and lift) on the cylinder were directly measured using a peizoelectric load cell, in conjunction with measurements of the wake flow pattern using digital Particle Image Velocimetry (PIV) for some cases. The results reveal that the grooved and dimpled cylinders produce a lower mean drag than that of a smooth cylinder. The strength of vertex shedding from the cylinder becomes weaker due to the effect of grooved or dimpled surfaces, as indicated by a smaller and narrower wake than that of the smooth cylinder. Highlights: This study shows experiment on forces and wake flow characteristics of cylinders. Grooved or dimpled surface is effective in reducing drag and r.m.s. lift coefficients. PIV results show that grooved or dimpled surfaces suppress the recirculation region. The strength of vertex shedding becomes weaker due to grooved or dimpled surface.