Yano T.

Nonlinear acoustic resonance of cylindrical waves of fluids is known to be a shock free oscillation. Owing to the absence of energy dissipation by the shock wave, the amplitude of resonance of cylindrical waves reaches of the order of cubic root of the acoustic Mach number at the sound source, while the amplitude of resonance of plane waves is limited to the order of square root of the acoustic Mach number by the energy dissipation at the shock front, where the acoustic Mach number is sufficiently small compared with unity usually in the nonlinear acoustics. Since the wave amplitude is very large, the velocity of the induced acoustic streaming is quite large as compared with that in the case of plane wave resonance, because acoustic streaming is one of the second order nonlinear phenomena. The large flow velocity means the large Reynolds number of the streaming motion concerned. We numerically examine the behavior of acoustic streaming of large Reynolds number induced by the resonance of cylindrical waves by solving the equations of fluid dynamics with a finite-difference method. Thereby, we clarify how the flow pattern of acoustic streaming changes as the Reynolds number increases, particularly focusing upon the breaking of geometrical symmetry of flow patterns.