Using corner chamfers to reduce the drag of flat-sided columns

Abstract

A comprehensive study of the drag forces acting on flat-sided columns is presented. The study considers a range of plane-sided column sections, from a sharp-cornered square section to varying degrees of corner chamfering and a full octagonal section. All chamfering was found to reduce the drag compared with the sharp-cornered case. It was also found there is a slight decrease in the drag coefficient as the Reynolds number of the fluid increases. For all cases except the octagonal section, drag increases significantly with increasing angle of attack. For the octagonal section, the drag coefficient increases then decreases as the angle of attack changes. The results agree with corresponding cases in the literature. The results are presented in a sequence of tables that allow users to estimate drag coefficients for any of the cases presented in the paper. As such, the study can serve as an archival repository for drag coefficient information. Comparisons of flow patterns are made, particularly in the wake region. It was found that the wake region becomes smaller as the chamfer becomes larger. The findings are important for the prediction of dynamic loads on exposed flat-sided columns above and below water, such as bridge pylons and offshore platform legs.