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Fig.2 Boundary Separation contributing to Swing
The Fast Bowler
To obtain conventional swing as a fast bowler
 The ball i...
The Impact of Science
on Bowling.
“the beauty of this sport lies
when the bowler and the
batsman try to dominate each
othe...
practitioner leaflet ss6022 13170651 Geoff Kenny
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practitioner leaflet ss6022 13170651 Geoff Kenny

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practitioner leaflet ss6022 13170651 Geoff Kenny

  1. 1. Fig.2 Boundary Separation contributing to Swing The Fast Bowler To obtain conventional swing as a fast bowler  The ball is released with the seam at an angle to the initial line of flight.  Over a certain Reynolds number range (>65mph), the seam trips the laminar boundary layer into turbulence (Fig. 2) on one side of the ball.  Whereas on the other (non-seam) side remains laminar (Fig. 2).  By virtue of its increased energy, the turbulent boundary layer, separates later (further back along the ball surface) compared to the laminar layer and so a pressure differential, which results in a side force, which makes the ball deviate from its line of path i.e. swing. MSc Sports Performance Physical Education and Sports Sciences Department Developed by the MSc Sports Performance Program 2014. A Practitioner Information leaflet on Fluid Dynamics, flow and streamlining in Cricket Contact Us Phone: + 353 61 202896 Email: PESS@ul.ie Web: www.ul.ie/pess/ CRICKET THE BOWLERS EDGE The Impact of Science on Bowling. Fluid Dynamics, flow and Streamlining in Cricket CRICKET THE BOWLERS EDGEThe Impact of Science on Bowling Fluid Dynamics, Flow and Streamlining in Cricket
  2. 2. The Impact of Science on Bowling. “the beauty of this sport lies when the bowler and the batsman try to dominate each other for supremacy” Getting the Edge: There are five main components in determining a cricket balls flight path: 1. Seam Angle 2. Velocity (Reynolds Number) 3. Drag (Surface Friction) 4. Boundary Separation 5. Spin Rate (Magnus Force) There are two vital phases during the delivery a bowled cricket ball. Phase 1: The ball undergoes free flight from the point it is released from the bowler’s hand until it hits the crease. During this phase the motion of the ball is entirely under the influence of aerodynamic forces and the bowler is capable of controlling its motion to a considerable extent. Phase 2: Involves the travel of the ball towards the batsman after bouncing off the crease. During this phase the motion of the ball is basically governed by the orientation of the ball when it bounces off the crease and the condition of the crease and hence the bowler has less control on the ball. The aerodynamics of a cricket ball depend on two possible states of the outer layer (boundary layer). Laminar - in which the flow is regular, smooth and barely parallel to the surface. Turbulent - where the general average motion is roughly parallel to the surface but there are rapid random fluctuations in velocity, direction and magnitude. Fig.1 Magnus Effect Spin Bowling The Spin Bowler To obtain conventional spin as a spin bowler  When spin is about the seam of the ball.  The ball bores through the air like a drill.  Creating low pressure on the top and high on the bottom. Creating uplift. (Fig.1)  Because of symmetry on each side of the seam, no lateral force will be generated.  Spin can also take place about any other inclined axis passing through the center of the ball.  Height, distance and curve of the ball will be dictated by the amount of rotational forces applied by the bowler to the ball i.e. spin.

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