Transitoire et changement de régime des écoulements redressés de Rayleigh à forts niveaux : Etudes numérique et expérimentale

Acoustic streaming is a second order flow associated with an acoustic wave and generated by the interaction between the wave and a solid wall. In the case of a stationary plane wave at low amplitude i.e. for slow streaming flow, the behaviour of this second order flow is well known: the streaming velocity along the resonator axis is a quadratic function of the acoustic velocity amplitude. For higher acoustic levels i.e. fast streaming flow, a previous numerical study (Inertial effects on non linear acoustic streaming, V. Daru, D. Baltean Carles, C.Weisman, AIP Conf. Proc. 1685, 030003 (2015)) has shown that this streaming velocity becomes a linear function of the acoustic velocity amplitude. In this new flow regime, additional streaming cells has been observed inside the resonator. In the present work, experimental results are presented that confirm the numerical observations. LDV measurements are conducted on a system of different physical dimensions from but similar asymptotic scales as the numerical study. The order of magnitude of streaming velocities on the resonator axis and in the near-wall region are compared for both flow regimes. Transient evolution of streaming velocity for various locations are also analysed for both flow regimes in order to point out the associated characteristic time scales.