Flow characteristics around a square cylinder with changing chamfer dimensions

Abstract

It is known that for a square cylinder subjected to uniform flow, the drag force changes with the angle of attack. To clarify the flow characteristics around a square cylinder with corner cutoffs, we measured the drag coefficient and the Strouhal number for changing chamfer dimensions. We analyzed the flow around a square cylinder with corner cutoffs by applying the RNG k-e turbulent model, and investigated the surface flow pattern using visualization by means of the oil film and mist flow method. From these results, we obtained the surface flow patterns by the oil film method and numerical analysis. The numerical results agreed well with the experimental values. The drag coefficient of the square cylinder with corner cutoffs decreased suddenly at an angle of attack of about a = 0°-10°when compared with the drag coefficient for a square cylinder. The minimum value of the drag coefficient for the square cylinder with corner cutoffs decreased by about 30% compared with that for the square cylinder. The drag coefficient of the square cylinder with 10% corner cutoffs was found to be smallest, since the wake area of this square cylinder was smaller compared with that of the other square cylinder.

An Experimental Study on the Wind-Induced Response of Variable Message Signs

“…The drag coefficient reductions for the chamfered and the round corner models are 18 and 29%, respectively. These results agree qualitatively with Tamura and Tetsuya (1999) and Yamagishi et al (2010). Results for wind speed of 40 m/s shows that though the chamfered corner model results were insensitive to Re effects, the round corner model results were sensitive to Re effects.…”

Aerodynamic Testing of Variable Message Signs

“…Visualization techniques also confirmed that the drag coefficient increased as the width of the wake behind the cylinder became larger Yamagishi et al (2010). It should be noted that in tall building design, corner geometry changes have played an important role in reducing wind loads.…”

“…Tamura and Miyagi (1999) concluded that corner modification decreases the wake width and promotes reattachment resulting in reduced drag forces. to approximately 1.5 for C5 (C/d = 0.167) Yamagishi et al (2010). Visible flow patterns obtained by Yamagishi et al (2010) using a propylene glycol mist tracer showed that the separation area of C3 was smaller than the areas for the sharp edge square and C5.…”

“…to approximately 1.5 for C5 (C/d = 0.167) Yamagishi et al (2010). Visible flow patterns obtained by Yamagishi et al (2010) using a propylene glycol mist tracer showed that the separation area of C3 was smaller than the areas for the sharp edge square and C5. They also noted that the tangential velocity of the corner end side of C5 was large compared to C3 which they thought contributed to the enlarged separation area of C5 and increased drag (the drag coefficient for C5 was still smaller than the cylinder with square corners).…”