“…Experiments by Higuchi and Kiura [38] show that a variation of only one degree (36 to 37 • ) in the stitch position causes a sudden separation. Moreover, they reported that the balls are more susceptible to hysteresis (including induced rotation) at the zones of separation.…”
Section: The Seams and The Boundary Layermentioning
confidence: 99%
“…Investigations carried out in the present decade show structured oscillations of drag coefficient despite the turbulence present in the phenomenon. For example, the experiment by Higuchi and Kiura [38] with different configurations of the ball, namely, the four-seam (4S), the twoseam (2S) and an arbitrary orientation of the ball 1 . They found the largest variation in oscillations for the 4S orientation, which is about twice as large as the case of the 2S orientation and around four times that of the arbitrary orientation.…”
Section: The Drag Force In Non-spinning Pitchesmentioning
“…Experiments by Higuchi and Kiura [38] show that a variation of only one degree (36 to 37 • ) in the stitch position causes a sudden separation. Moreover, they reported that the balls are more susceptible to hysteresis (including induced rotation) at the zones of separation.…”
Section: The Seams and The Boundary Layermentioning
confidence: 99%
“…Investigations carried out in the present decade show structured oscillations of drag coefficient despite the turbulence present in the phenomenon. For example, the experiment by Higuchi and Kiura [38] with different configurations of the ball, namely, the four-seam (4S), the twoseam (2S) and an arbitrary orientation of the ball 1 . They found the largest variation in oscillations for the 4S orientation, which is about twice as large as the case of the 2S orientation and around four times that of the arbitrary orientation.…”
Section: The Drag Force In Non-spinning Pitchesmentioning
“…1 Thus, the aerodynamically induced motion of sports balls has long been a subject of interest to players and physicists alike. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Pitchers take advantage of these effects with an arsenal of different breaking pitches: sliders and curveballs, sinkers, cutters, and the ever-confounding knuckleball. Each pitch is delivered with aerodynamics in mind, from the way the pitcher grips the ball and aligns the seams, to the initial velocity, spin, and axis of rotation.…”
Section: A Knuckleball Backgroundmentioning
confidence: 99%
“…Figure 3 presents the averaged dimensionless lift from a non-spinning ball in a 4S orientation as a function of ball angle at a Reynolds number of 1.6 Â 10 5 . The data of Watts and Sawyer 7 and Higuchi and Kiura 19 are presented for comparison. Pictures illustrating the seam locations for corresponding ball angles are displayed directly below the x-axis for reference.…”
Section: Force Measurements: Four-seam (4s) Orientationmentioning
confidence: 99%
“…D. Force measurements: Two-seam (2S) orientation Figure 5 presents the lateral and lift force for a nonspinning baseball in a 2S orientation obtained at a Reynolds number of 1.6 Â 10 5 . Included on this figure are data obtained from Higuchi and Kiura 19 and a pitch window, illustrated as a shaded region from 120 to 300 , which represents the desired ball rotation of Dickey and Wakefield. 22,23 The lift and lateral force data for the 2S pitch contain much more structure compared to the 4S pitch.…”
Section: Force Measurements: Four-seam (4s) Orientationmentioning
In this work, we characterize the lift and lateral forces on a two-seam versus four-seam knuckleball and measure the viscous shear stress. We believe these measurements to be the first reported for slowly rotating baseballs. Our findings indicate the seam acts to either delay or advance separation depending upon the ball angle; these results are supported with flow visualization. The combined effect produces significant lift and lateral forces that can rapidly change as the ball rotates. Furthermore, we found the shear stress to be asymmetric which can result in significant in-flight torque. Together, asymmetries in force and shear stress produce the complicated flight trajectories that can confound the hapless batter.
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