SOUND GENERATION BY A VORTEX RING COLLISION

A collision between two vortex rings and its sound generation is studi ed numerically using the contour dynamics method. Results suggest that the radial acceleration and the rate of change of the axial accelerat ion of the vortex rings are the more important dynamic parameters for sound generation during the interaction. The former is important at or near the pass-through instant when the vortex rings are coplanar and are of unequal strength. The latter, being important in the sound gene ration during a head-on collision before the vortex ring cores are ver y close to each other, especially when the rings are thin, is also imp ortant in sound generation by an unequal strength vortex ring collisio n after the pass through when the vortex cores are separated by a dist ance so that the mutual induction strength does not result in signific ant change of the impulse of the stronger ring. (C) 1995 Acoustical So ciety of America.