The ping‐pong cannon demonstration: Optical studies and numerical simulation

This presentation describes the use of laser pulse photography, optical timing, pulsed Schlieren, and heterodyne interferometry to look more closely at the fluid dynamics of a recently popular lecture demonstration—the so‐called ‘‘ping‐pong cannon.’’ Optical diagnostic techniques have been applied to two types of these cannons, and led to greater knowledge of the kinematics of the accelerating ball, along with some insight into the exit mechanism and subsequent target interactions. Also will be described how a 1D numerical simulation allows visualization of shock wave formation within the tube during ball acceleration. Solutions of the Euler equation are obtained using the method of space‐time finite elements, while the ball is tracked as an interface in the compressible fluid mesh. [Work supported in part by the MN NASA Space Grant and the Carlsen‐Lewis Endowment of Bethel University.]