Reduction of drag of a submerged swimmer using vortex generators

Regions of separated flow constitute a significant source of drag for competitive swimmers particularly during the submerged portions of the race, which occur immediately after each start and turn. Since races are frequently decided by fractions of a second, even modest drag reductions could have a significant effect on the outcome of a competition.; The author has proposed the use of vortex generators to minimize separation bubbler, thereby reducing overall swimmer drag. The purpose of this research project was to determine the optimal type, size and arrangement of vortex generators to minimize overall drag.; To this end, drag measurements of a one half-scale model of a swimmer with various vortex generators were taken in Carleton University's closed-circuit low-speed wind tunnel. The results suggest that vortex generators could reduce the drag coefficient for a submerged swimmer by as much as six percent. The minimum drag for a practical configuration was achieved with a double inline row of Kuethe type vortex generators of approximately one-tenth inch scale height (one twentieth of an inch on the model).; This configuration was incorporated into a swimsuit worn by American swimmers at the 1996 Atlanta Olympic games (Jenny Thompson won three relay gold medals) and the 1998 World Championships in Perth Australia (various medals and records).