Redshift of the ultrasonic wave frequency in acoustic streaming

Redshift of the ultrasonic wave frequency is observed in acoustic streaming. According to quantum mechanics, a redshift (i.e., frequency decline) indicates energy loss. The driving force of acoustic streaming is derived from the Hamiltonian, in which acoustic energy is represented by the phonon scheme. The driving mechanism of acoustic streaming involves the direct energy transfer from the acoustic energy to the kinetic energy of the medium. The possibility of macroscopic quantum effects is shown in the experimental data of redshift of the ultrasonic wave frequency in acoustic streaming.