Aerodynamics of Odd Balls

A wiffle ball is an odd sort of ball — a hollow plastic sphere with lots of holes cut away in a particular pattern. It makes for odd-seeming physics. For a deep-announcer-voiced-with-pounding-music look at what wiffle balls do, see the video below.

Dana Mackenzie in Wired magazine wrote a report called “Mechanical Engineer Explains the Secrets of the Wiffle Ball“. (Thanks to investigator Scott Langill for bringing this to our attention.) The hero of the tale is Professor Jenn Rossmann [pictured here] of Lafayette College.

Rossmann’s research was presented in 2003 at a scientific meeting: “Aerodynamics of Wiffle Balls,” Alexis Utvich, Colin Jemmott, Sheldon Logan and Jenn Rossmann, American Physical Society, Division of Fluid Dynamics 56th Annual Meeting, November 23-25, 2003, East Rutherford, New Jersey, MEETING ID: DFD03, abstract #MJ.005. The abstract explains:

“A team of undergraduate students has performed experiments on Wiffle balls in the Harvey Mudd College wind tunnel facility. Wiffle balls are of particular interest because they can attain a curved trajectory with little or no pitcher-imparted spin. The reasons behind this have not previously been quantified formally…. A fog-based flow visualization system was developed in order to provide a deeper qualitative understanding of what occurred in the flowfield surrounding the ball. The data and observations obtained in this study support existing assumptions about Wiffle ball aerodynamics and begin to elucidate the mechanisms involved in Wiffle ball flight.”