MEASUREMENT OF THE ESTABLISHMENT PROCESS OF ACOUSTIC STREAMING USING LASER-DOPPLER VELOCIMETRY

Acoustic streaming generated by 5.05 MHz CW ultrasound in water has be en measured using a laser Doppler velocimeter to clarify the establish ment process of the streaming. When the ultrasound is switched on, the streaming velocity along the beam axis increases, monotonously approa ching a steady value as long as the applied voltage to the transducer is low. At a farther distance from the transducer, it takes more time to settle down and some cases show overshooting in the velocity change s. At higher voltages, the streaming velocity increases rapidly and th ere appears anomalous behavior in the establishment process showing pl ateaus and humps.