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

Abstract

Purpose

The paper aims to study the influence of rounded corners on the flow-induced oscillation of a square cylinder that is free to oscillate in two degrees of freedom.

Design/methodology/approach

The finite volume code in conjunction with the moving mesh scheme was implemented via a user-defined function to carry out the computations in two dimensions. The Reynolds number (Re) chosen for the present study is fixed at 100, and the frequency ratio, F_r = f_s/f_n (where f_s is the vortex shedding frequency and f_n is the natural frequency of cylinder) is used as a varying parameter. The computational model was validated for flow past a stationary cylinder with R/D = 0 and 0.5, and the results showed good agreement with the literature.

Findings

The aerodynamic characteristics, amplitude response, trajectories of cylinder motion and vortex shedding modes are obtained by conducting a series of simulations under different frequency ratios of the cylinder. It was found that the minimum transverse amplitude, drag force and lift force obtained for a naturally oscillating square cylinder are quite different when compared with a stationary and forced oscillating cylinder, where the maximum drag and lift forces were observed for a square cylinder and a minimum around R/D = 0.2 was observed.

Originality/value

The present work identified the significant effect of the varying frequency ratio and R/D on the VIV modes of the cylinder. It was observed that the cylinder wake exhibits the (2S) vortex shedding mode for R/D = 0 to 0.2 at all F_r, whereas the C (2S) mode appeared for R/D > 0.2 at F_r = 1.1.

Citation

Miran, S. and Sohn, C.H. (2017), "Effect of rounded corners on two degree of freedom naturally oscillating square cylinder", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 27 No. 10, pp. 2355-2374. https://doi.org/10.1108/HFF-06-2016-0248