Aerodynamic Effects of Dimple Placement in Speed Skating Suit Fabrics

This study investigates how dimple arrangement and exposed fabric surface condition influence the aerodynamic characteristics of speed skating suit fabrics. Four fabric configurations were compared: DI, with the dimpled surface placed inward; DO, with the dimpled surface exposed outward; NI, with the smooth standard surface exposed to the flow; and NO, with the rougher reverse side of the standard fabric exposed outward. Fabric specimens of 10 cm × 25 cm were attached to both sides of a symmetric wing-shaped model, and wind tunnel tests were conducted at flow velocities from 10 to 20 m/s.

From a Manufacturing Technologies perspective, this study is meaningful because it treats dimple placement and exposed surface orientation as textile-design and garment-manufacturing variables that may affect aerodynamic performance. The drag coefficient was calculated using the total attached fabric area and interpreted as a fabric-area-normalized coefficient for relative comparison, rather than as a conventional whole-body drag coefficient.

The results showed that NI consistently produced the lowest drag and drag coefficient across the tested velocity range, whereas DO showed the highest values. In the representative skating speed range of 13–15 m/s, DO exhibited approximately 31.9–40.0% higher drag coefficients than NI. DI showed intermediate aerodynamic behavior, suggesting that placing the dimpled structure inward while maintaining a smoother outer surface was more favorable than exposing the dimples directly to the airflow. NO also showed intermediate behavior but tended to increase at higher Reynolds numbers.

Overall, the findings suggest that outward dimple exposure did not reduce drag under the present simplified conditions. Instead, smooth external surface design appeared more favorable. However, because the experiment used a simplified wing-shaped model and only two repeated trials, further validation using full-body models, fabric stretch conditions, larger repeated trials, and flow visualization is required before applying the findings directly to competition suit manufacturing.