Effect of shape modification on heat transfer and drag for fluid flow past a cam-shaped cylinder

Abstract

In this study, a cam-shaped cylinder immersed in the cross-flow is investigated numerically, which is made of two circular cylinders joined by their two common tangents. The equivalent diameter of the cam-shaped cylinder Deq is constant, which is maintained by adjusting the diameters of and the distance between the front and rear cylinders. The present study systematically investigates the effects of shape transformation of a base circular cylinder into different shapes of the cam-shaped cylinder on the flow and heat transfer characteristics. The cam-shaped cylinders with different relative diameter ratios of cylinder 1 (D1/Deq = 0.2–0.84), and different relative diameter ratios of cylinder 2 (D2/Deq = 0.5–0.9) for the two Reynolds numbers (Re = 100, and 200) are considered. The functional dependence of drag coefficient (CD) and lift coefficient (CLmax) on D1/Deq and D2/Deq are examined. CD decreases with an increase in Re and a decrease in D2/Deq, respectively, while the Strouhal number (St) increases with a decrease in D2/Deq. The average Nusselt number (Nu‾) increases with an increase in Re and decreases with a decrease in D2/Deq. The change in Nu‾ is almost negligible for a low D1/Deq. Different regimes are proposed for the design parameters selection for high Nu‾ and low CD. In the regime of constrained design and flow conditions, the present cam-shaped cylinders show their superiority over the other bluff bodies in terms of enhanced heat transfer and reduced drag.