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Cricket ball swing and airfoils

  1. May 15, 2009 #1
    I'm a fan of cricket. I've always wondered how bowlers get cricket balls to swing in the air. According to the two articles at the following sites http://web.archive.org/web/20061230003022/www.soest.hawaii.edu/GG/STUDENTS/jfoster/normal.html" [Broken]
    http://content.cricinfo.com/ci/content/story/258645.html" [Broken]
    the swing of the cricket ball through the air is due to the pressure difference caused by air flow over the ball.
    Both articles say that the turbulent air flow generated separates from the surface of the ball later than the separation of laminar flow occurs and claim that this creates lower pressure on the side of turbulent flow.. Why is this? I though that, if the flow of air separates from the surface, it creates low pressure because there is a "gap" which contains "nothing" between the air flow and the ball(as with the laminar flow) and if it stays close to the surface, it will not create low pressure.
    Furthermore if turbulent air flow creates low pressure then why would an aircraft wing stall? In a stall, the air flow over the wing becomes turbulent and I know, that at that point, the wing stops flying and starts falling. If turbulent air flow creates low pressure like the articles suggest then the wing would simply develop more lift.

    (I don't know if it's relevant but I do know that the "Bernoulli explanation " of how airfoils work is incorrect
    Last edited by a moderator: May 4, 2017
  2. jcsd
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