Near field acoustic streaming jet

Brahim Moudjed (1) , Valéry Botton (1) , Daniel Henry (1) , Séverine Millet (1) , Jean-Paul Garandet (2, 3) , Hamda Ben Hadid (1)

1 LMFA - Laboratoire de Mecanique des Fluides et d'Acoustique
2 DTS - Département des Technologies Solaires
3 INES - Institut National de L'Energie Solaire

A numerical and experimental investigation of the acoustic streaming flow in the near field of a circular plane ultrasonic transducer in water has been performed. The experimental domain is a parallelepipedic cavity delimited by absorbing walls to avoid acoustic reflection, with a top free surface. The flow velocities are measured by PIV, leading to well resolved velocity profiles. The theoretical model is based on a linear acoustic propagation model, which correctly reproduces the acoustic field mapped experimentally using a hydrophone, and an acoustic force term introduced in the Navier Stokes equations under the plane wave assumption. A good agreement between the experimental measurements and the numerical results for the velocity field is obtained, validating our numerical approach. The flow structure is found to be correlated with the acoustic field shape. Indeed, the longitudinal profiles of the velocity present a wavering linked to the variations in acoustic intensity along the beam axis and transverse profiles exhibit a complex shape strongly influenced by the transverse variations of the acoustic intensity in the beam. Finally the velocity in the jet is found to increase as the square root of the acoustic power times the distance from the origin of the jet over a major part of the cavity.

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Brahim Moudjed, Valéry Botton, Daniel Henry, Séverine Millet, Jean-Paul Garandet, et al.. Near field acoustic streaming jet. 2014. ⟨hal-01062580v1⟩