Numerical Simulation and Investigation of Flow Patterns Around Three Side-by-Side Cylinders Arranged in Line with an Oscillating Central Cylinder

A flow past three cylinders arranged in a vertical row in a side-by-side configuration in which both side cylinders were kept fixed and an oscillatory movement provided to the middle cylinder was simulated. This particular configured setup holds significant importance in engineering and presents a compelling resemblance to numerous real-world scenarios especially in electricity production using oscillatory motion. In the present study, free-stream flow across three side-by-side cylinders with a transversely oscillating middle cylinder, was simulated using the commercial CFD software tool ANSYS 2021 R2 at a low Reynolds number (Re) = 100, with non-dimensional cylinder spacing (s/d) = 2;. For the middle cylinder, non-dimensional amplitude (amplitude ratio), A/d = 0.5 and a frequency ratio of fe/fo=0.8, 1 and 1.2 were considered (fe/fo, where fe is the cylinder oscillation frequency and fo is the corresponding vortex shedding frequency for stationary cylinders). In this study, re-meshing was done using the dynamic mesh technique, and pre-defined oscillatory motion was provided with the help of an additionally hooked User Defined Function (UDF) in the commercial CFD software tool. The objective of the present study was to investigate the effect of governing parameters on flow physics and wake nature, as well as the effect of the flow transition on engineering parameters. The interesting finding to report here that for oscillation frequency fe/fo= 1 there exist synchronous flow confirmed from wake diagram having comparatively more drag with that of other two higher fe/fo= 1.2 and lower oscillation frequency ratio fe/fo= 0.8 for cylinder spacing (s/d) = 2.