Özgören, MuammerDoğan, SercanOkbaz, AbdulkerimAksoy, Muharrem HilmiŞahin, BeşirAkıllı, Hakan2020-03-262020-03-262013978-80-7372-912-72100-014Xhttps://dx.doi.org/10.1051/epjconf/20134501022https://hdl.handle.net/20.500.12395/293157th International Conference on Experimental Fluid Mechanics (EFM) -- NOV 20-23, 2012 -- Tech Univ Liberec (TU Liberec), Hradec Kralove, CZECH REPUBLICComparison of the experimental results of turbulent flow structures between a smooth sphere and a sphere with a vent hole, roughened, and o-ring is presented in the presence of a free-surface. Dye visualization and particle image velocimetry (PIV) techniques were performed to examine effects of passive control methods on the sphere wake for Reynolds number Re = 5000 based on the sphere diameter with a 42.5mm in an open water channel. Instantaneous and time-averaged flow patterns in the wake region of the sphere were examined from point of flow physics for the different sphere locations in the range of 0 <= h/D <= 2.0 where h was the space between the top point of the sphere and the free surface. The ratio of ventilation hole to sphere diameter was 0.15, o-ring was located at 55 degrees with a 2 mm from front stagnation point of the sphere and roughened surface was formed by means of totally 410 circular holes with a 3 mm diameter and around 2 mm depth in an equilateral triangle arrangement. The flow characteristics of instantaneous velocity vectors, vorticity contours, time-averaged streamline patterns, Reynolds stress correlations and streamwise and cross-stream velocity fluctuations for both the smooth and passively controlled sphere were interpreted.en10.1051/epjconf/20134501022info:eu-repo/semantics/openAccessConference Object45N/AWOS:000319932200022N/A