Effects of afterbody shape on flow around prismatic cylinders

The effects of the afterbody shape on the structure of the flow past a prismatic cylinder were investigated numerically. The shape of the cross-section of the cylinder varies from the square to trapezoids and finally to the triangle. Flow characteristics of vortex formation and shedding after the cylinder as well as its interaction with the separating shear layer from the leading edges were revealed by studying the patterns of instantaneous streamlines and the time-dependent pressure distribution on the surface of the cylinder. The present results show that when the ratio of rear and front width, λ<0.5, the vortex shedding frequency increases with the increase of λ, but when λ>0.5, the frequency decreases with the increase of λ. The mean value of the drag coefficients decreases monotonously with the increase of λ. Comparisons with experimental data and visualized flow field are included. Findings from this research are very useful for prismatic tower structures.