Experimental investigation of flow around horizantal circular cylinders

Two-dimensional submerged circular cylinders are widely used structural elements in engineering practices, and therefore the studies on the interaction of such bluff bodies with the fluid flow are important for design considerations. The vertical gap distance between the horizontal cylinder and a plane boundary is the major parameter that affects the disturbed flow structure around cylinder. In this study, using particle image velocimetry technique, experiments are conducted to measure the velocity field of flow around a horizontal circular cylinder having a diameter of D=50 mm with seven different gap ratios, G/D=0.0, 0.1, 0.2, 0.3, 0.6, 1.0, 2.0, and for two Reynolds number conditions, ReD=4150 and 9500. Using the experimental results, the effect of gap ratios for different Reynolds number conditions on the various properties of the affected flow field such as the velocity distribution around cylinder, wall boundary layer separation, position of stagnation and separation points on the cylinder, and the Strouhal number for the vortex shedding frequencies are investigated. The experimental results indicate that the wall proximity effect on velocity fields is almost negligible for G/D?1.0. Additionally, using the ANSYS program package, numerical analysis is also carried out to compute the velocity field of flow at G/D=0.3 and ReD=9500. The results show that the numerical velocity field is quite in agreement with the experiment. Keywords: Steady Flow, Circular Cylinder, Particle Image Velocimetry, Wall Effect, Velocity Field.