Flow past two tandem square cylinders placed in parallel walls

Abstract

In this work, pulsating and non-pulsating flow structures past two tandem square cylinders placed in parallel walls was investigated. The variation of the distance between the cylinders and the frequency of flow pulsation was also examined. The Particle Image Velocimetry (PIV) method was applied to reveal hydrodynamic characteristics such as streamlines patterns, <Ψ>, the velocity vector distribution, the vorticity field, <ω>, the normalized streamwise velocity contours, <U/Uavg>, and turbulent statistics such as streamwise velocity fluctuations, urms, cross-streamwise velocity fluctuations, vrms, and turbulent Reynolds stress, u′v′‾/U02 distributions for non-pulsating flow cases. In addition, instantaneous and phase averaged flow data over the flow field is presented in order to evaluate the influence of flow pulsation on the quantitative analyses. The experiments were performed at Re=500. According to the results, the confinement profoundly affects the flow regime past two tandem cylinders. The alteration from the reattach flow to the co-shedding vortex flow regime take place at a lower gap ratio. Moreover, flow pulsation considerably contributes to mainstream penetration into the gap between cylinders. The mechanism of the fluid interactions near the wall and mainstream is highly dependent on the ratio of L/D and pulsation frequency.