Flow comparison around horizontal single and tandem cylinders at different immersion elevations

Flow characteristic around a horizontal cylinder and tandem horizontal cylinders were compared in shallow water of which height was kept constant as hw = 60 mm in this study. The other parameters, taken constant, were free stream velocity and diameter of circular cylinders of which values were U = 167 mm/s and D = 30 mm, respectively. To evaluate the time-averaged and instantaneous velocity vector area in the wake zone at Reynolds number; ReD = 5000 basis on the diameter of cylinder, Particle Image Velocimetry (PIV) was operated. The gap (L) between the tandem cylinders was enhanced from 0 until 90 mm through 15 mm enhancements and it was enhanced from 90 up to 150 mm through 30 mm enhancements in order to observe effect of the gap on flow characteristics. Moreover, another important parameter was the submersion level that ranged from 7.5 until 60 mm through 7.5 mm increments (hD/D = 0.25–2) during the experiments. Five hundred instantaneous images were used in order to obtain Reynolds stress correlation, corresponding streamline topology and the mean velocity vector field. The investigation represented that the alternative cylinder attenuates the dimension of the wake zone in accordance with L/D = 0 location. The wake zone obviously happens between tandem cylinders at the starting of L/D = 1 location. When the space between tandem cylinders deepens the dimension of the wake zone rises. © 201