Generation of microbubbles from hollow cylindrical ultrasonic horn

► A hollow cylindrical ultrasonic horn can easily generate microbubbles. ► The breakup of bubbles oscillating harmonically with the ultrasonic irradiation generates many microbubbles. ► Increasing the gas flow rate and the ultrasonic power input can increase the number of microbubbles. ► The optimum value of the orifice diameter of the horn end varies with the ultrasonic power input.