Numerical study of the rounded corners effect on flow past a square cylinder

Abstract

Purpose -The purpose of this paper is to numerically investigate the influence of corner radius on flow past a square cylinder at a Reynolds number 500. Design/methodology/approach -Six models were studied, for R/D ¼ 0 (square cylinder), 0.1, 0.2, 0.3, 0.4, and 0.5 (circular cylinder), where R is the corner radius and D is the characteristic dimension of the body. The transient two-dimensional (2D) laminar and large eddy simulations (LES) models were employed using finite volume code. The Strouhal number, mean drag coefficient (C D ), and root mean square (RMS) value of lift coefficient (C L,RMS ), for different R/D values, were computed and compared with experimental and other numerical results. Findings -The computational results showed good agreement with previously published results for a Reynolds number, Re ¼ 500. It was found that the corner effect on a square cylinder greatly influences the flow characteristics around the cylinder. Results indicate that, as the corner radius ratio, R/D, increases, the Strouhal number increases rapidly for R/D ¼ 0-0.2, and then gradually rises between R/D ¼ 0.2 and 0.5. The minimum values of the mean drag coefficient and the RMS value of lift coefficient were found around R/D ¼ 0.2, which is verified by the time averaged streamwise velocity deficit profile. Originality/value -On the basis of the numerical results, it is concluded that rounded corners on a square cylinder are useful in reducing the drag and lift forces generated behind a cylinder. Finally, it is suggested that with a rounded corner ratio of around R/D ¼ 0.2, the drag and oscillation of the cylinder can be greatly reduced, as compared to circular and square cylinders.

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

“…Similarly, a C-type mesh for the region in front of the cylinder and a coarse mesh for the rest of the flow field were distributed. The influence of the spatial and temporal resolutions and the computational domain independence was discussed in detail by (Miran and Sohn, 2015) for the flow past square and circular cylinder geometries. A grid size consists of 62,800 elements chosen for this study was based on the grid independence study reported by Miran and Sohn (2015).…”

Vortex Shedding Suppression: A Review on Modified Bluff Bodies

“…Therefore, it was reported that the leading edge corner modification is more effective on the flow structure in comparison with the trailing edge corner modification. Miran and Sohn [36] performed a numerical study to investigate the effect of rounded corners on the flow structure past a square cylinder for various corner radii ranges from R/D (where R is the corner radius and D is the characteristic dimension of the body) 0 to 0.5. It was observed that the corners affect the flow characteristics significantly.…”

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

“…In the region around the cylinder wall, fine O-type mesh was used to accurately capture the flow behavior near the cylinder walls. The grids used in all cases consist of 62,800 elements and are based on the grid independence study reported by Miran and Sohn (2015). Three different grid sizes (G1-40680, G2-62800 and G3-91530) were used to investigate the influence of the grid refinement effect on the solution.…”

“…They found that the leading-edge corner radius has greater influence in the near wake structure because it determines to a great extent the behavior of the streamlines, the separation angle and the base pressure. 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.…”