Thermal and vibratory response of sprung square cylinder with four nature-inspired fin-shaped bumps

Abstract

Nature provides man with various interesting structures, offering him a constant source of manufacturing tools and invention. The main purpose of the present paper is to investigate the effect of shark-inspired fins, which are installed on the top and bottom plates of a sprung cylinder on the vibration response and heat transfer of square cylinder. Two fin sizes, i.e. small and big, are used. Three configurations for the fins on the top and bottom plates of the square cylinder are considered: at the corners of the square cylinder, spaced from the corners, and in the middle of the plates. The results indicate that adding fins increases the amplitude of vortex-induced vibrations and extends the lock-in region which is both intensified as the size of fins increases. In particular, for the cylinder equipped with small fins in configurations 1–3, the maximum VIV amplitude increases by, respectively, 36 %, 57 % and 52 % compared with the plain cylinder. In contrast, shark fins can lower the galloping amplitude by as much as 87 % and shrink the galloping zone such that for big fin size in the second and third configurations, the galloping zone and its corresponding vortex-shedding mode are not observed. Adding fins to the cylinder augments heat transfer. The increase in mean Nusselt number depends on vortex-shedding mode, and the rise in Nusselt number is higher in the 2P + 2S mode.