Influence of incidence angle on the aerodynamic characteristics of square cylinders with rounded corners

Abstract

Purpose – The purpose of this paper is to focus on the variation of wake structures and aerodynamic forces with changes in the cylinder corner radius and orientation. Design/methodology/approach – Numerical simulations were performed for flow past a square cylinder with different corner radii placed at an angle to the incoming flow. In the present study, the rounded corner ratio R/D=0 (square cylinder), 0.1, 0.2, 0.3, and 0.4 (where R is the corner radius and D is the characteristic dimension of the body) and the angle of incidence α in the range of 0°-45° were considered. Findings – The numerical model was validated by comparing the present results with results in the available literature, and they were found to be in good agreement. The critical incidence angle for the rounded corner cylinder – corresponding to the minimum mean drag coefficient (C D ), the minimum root mean square value of the lift coefficient C L,RMS), and the maximum Strouhal number – shifted to a lower incidence angle compared with the sharp corner square cylinder. The minimum drag and lift coefficient at R/D=0 were observed for the critical incidence angle αcri=12°, whereas for R/D=0.1-0.4, the minimum drag and lift coefficient were found to be within the range of 5°-10° for α. Originality/value – The presented results shows the importance of the incidence angle and rounded corners of the square cylinder for reduction of aerodynamic forces. The two parameters support the shear layer flow reattachment on the lateral surface of the cylinder, have a strong correlation with the reduction of the wake width, and hence reduced the values of C D and C L .

Vortex Shedding Suppression: A Review on Modified Bluff Bodies

“…It was reported that in the case of the cylinder with rounded corners these variations are less significant in comparison with cylinders with sharp corners. [45], Miran and Sohn [46] and Tong and Sparrow [47] investigated the effect of the angle of attack or incidence angle on the flow structure of square cylinders with modified corners. Carassale and Freda [45] investigated the influence of corner modification on the aerody- Some researchers combined the effect of corner modification with other parameters on the wake flow.…”

“…It was reported that rounded corners promote the reattachment of the flow on the lateral faces and as a result the critical angle of incidence was reduced. Miran and Sohn [46] observed that the rounded corner cylinder exhibits a lower critical incidence angle in comparison with the sharp corner square cylinder. Therefore, for R/D = 0 (square cylinder) a critical incidence angle of 12 • was observed whereas for R/D = 0.1-0.4 a value in the range of 5-10 • was reported.…”

A 3D Numerical Investigation into the Effect of Rounded Corner Radii on the Wind Loading of a Square Cylinder Subjected to Supercritical Flow

“…The results indicated that the length of the time-averaged recirculation region was highest for a corner radius ratio of r/D = 0.125. A study on the effect of the angle of incidence on the drag characteristics of a rounded corner square cylinder was presented in [21]. The drag coefficient attained minima when the angle of incidence was between 5 and 10 degrees.…”

Effect of rounded corners on two degree of freedom naturally oscillating square cylinder

“…Recently, Miran and Sohn (2015) numerically analyzed the effect of rounded corners on the stationary cylinder and found that a rounded corner ratio of approximately R/D = 0.2 -0.3 reduces the drag and lift forces. The influence of the incidence angle was also numerically studied by Miran and Sohn (2016a), who found that rounded corners are a strong function for reduction of aerodynamic forces irrespective of the incoming flow. Kumar et al (2009) used the PIV technique and found that rounded corners significantly influenced the flow features around the bodies.…”