Friday, 24 October 1986 12:00 p.m.
Aerodynamic Generation of Sound, The Movie (44 minutes)
directed and produced by Sir James Lighthill and J.E. Ffowcs Williams for the US Committee for Fluid Mechanics Films
The study of sound produced by a variety of sources usually requires the use of well-calibrated microphones, accelerometers, and anechoic chambers. However, simulations of sound generation sometimes give a clearer understanding of the phenomenon. Since the ripple speed in a glass-bottomed tank filled with 5 mm of water is independent of frequency, the ripples in a tank simulate wave motion in air. In this film Lighthill and Ffowcs Williams use a ripple tank to demonstrate the characteristics of monopole, dipole, and quadrupole acoustic sources and their interactions.