6. Ultrasonic process

6.1 Principle and mechanism

• Ultrasonic emission

  Power ultrasonics are sound waves with frequencies between 16 kHz (upper limit of human audibility) and 1 MHz. They are generally emitted by a flat surface vibrating sinusoidally around its equilibrium position, at frequency f and amplitude A (of the order of µm).

• Wave propagation

  The wave propagates in solid, liquid or gaseous media with a celerity c, which depends on the physical properties of the medium, and a wavelength λ(λ = c/f). In liquid media, the wave is assumed to be plane and longitudinal. The acoustic pressure P _A or overpressure with respect to...