Effect of Dimples for Fluid Motion of an Elastically Supported Cylinder at Velocities Relevant to Ducting Environment Using Computational Fluid Dynamics

This paper discusses the effect of dimpling on an elastic cylinder using computational fluid dynamics (CFD) simulation. The simulation CFD approach is used because it is low-cost. The purpose of this study is to model a cylinder that has three different cylinder surface configurations: smooth cylinder, outwardly dimpled, and inwardly dimpled on half the surface of the cylinder (front). This aims to increase the coefficient lift value of the cylinder and decrease the coefficient drag value in order to utilize it as alternative energy in the cylinder system supported by two beams. Furthermore, the numerical simulation is performed on an elastic cylinder with a velocity of 3.5 m/s and an aspect ratio (L/D) of 5.6. The time-domain responses of force coefficients and structural displacements are converted into frequency-domain responses using the Fast Fourier Transform to characterize the structure responses. The results demonstrate that the cylinder surface is very successful at improving the lift coefficient and decreasing the drag coefficient while maintaining the velocity constant. The time necessary to commence cylinder displacement varies depending on the circumstance. For an inwardly dimpled cylinder, the displacement initiation start time is 0.1 s; for a smooth and outwardly dimpled cylinder, the displacement initiation start time is 0.25 s. The highest vortex shedding frequency lift coefficient is obtained from an inwardly dimpled cylinder, followed by an outwardly dimpled cylinder, while the lowest is a smooth cylinder. While the frequency obtained due to changes in surface variation does not change significantly, which is around 15 Hz.