Effects of Seam Position and Seam-Folding Direction on the Aerodynamic Drag of Skiwear Fabrics

Aerodynamic drag is a key factor influencing performance in high-speed winter sports, and even small reductions in drag may contribute to meaningful improvements in race time. This study investigated the effects of seam position and seam-folding direction on the aerodynamic characteristics of skiwear fabrics using wind tunnel experiments with two simplified models: a cylinder model and a wing-shaped model. In the cylinder model, the seam position directly facing the airflow was defined as 0° and shifted in 30° increments, whereas in the wing-shaped model, the seam was moved rearward from the foremost point in 5 cm increments. The inward-folded portion of the seam was arranged either toward the airflow or opposite to it. Wind tunnel tests were conducted at wind speeds ranging from 40 to 120 km/h, and drag coefficients were calculated from measured drag forces. The results show that aerodynamic drag varied with seam position in both models. In the cylinder model, the lowest drag coefficient was observed at 30° from the front, whereas in the wing-shaped model, the lowest drag was obtained at the foremost seam position (0 cm). At 100 km/h, shifting the seam position from 0 cm to 5 cm increased the drag coefficient by approximately 54.5% in seam type A and 50.0% in seam type B. These findings suggest that seam position may be a potentially relevant aerodynamic design variable in skiwear research, whereas seam-folding direction appeared to be of secondary importance under the present test conditions. However, the present conclusions are restricted to simplified experimental geometries and should not be directly generalized to specific body regions or full-garment systems.