PIV measurement of flow over square cylinders in tandem arrangement

The aim of this thesis is to investigate the flow structure past two tandem square cylinders under shallow water condition by using Particle Image Velocimetry (PIV) technique. In all experiments, two plexsiglas square cylinders having the diameter of D = 28 mm were used. All experiments were carried out in 14 mm deep water and free stream velocity was U = 160 mm/s, corresponding to a Reynolds number value of 4470. Experiments were performed for three different types of view section; side view, plan view bottom plane (2mm), plan view mid-plane (7mm). The distance between the cylinders was changed between G=0 mm and 140 mm, which corresponds to a dimensionless gap ratio of G/D = 0 to 5. In order to understand the effect of the spacing between square cylinders, three sets of experiments were performed and each set includes 350 instantaneous images. In this way, average velocity vectors, streamlines, vortex structures and Reynold stresses were obtained. The results of the experiments reveal that the flow characteristics between the two cylinders are not affected from the presence of downstream cylinder when the gap ratio G/D exceeds 3.5.