Cavitation bubble collapse and its produced microjet on a solid wall are very important for the application of ultrasound. However, the prediction and control of microjets have been a very challenging work due to the complicated mechanisms of the collapsing of cavitation bubbles under the ultrasonic field. In order to determine the interaction of the microjet with the key parameters that influence the acoustic cavitation, the dynamics of bubble growth and collapse near a rigid boundary in water are investigated. Numerical simulations of the motion characteristics and collapsed velocities of a bubble near a rigid boundary and a free boundary have been performed. Compared with the free boundary, the rigid boundary has an inhibition effect for ultrasonic cavitation. The velocity of the bubble collapse under the rigid boundary is decreased as the increase of the initial bubble radius and ultrasonic frequency and rises with the increase of the distance from the bubble to the solid wall. There is the optimal acoustic pressure at which ultrasonic cavitation effect near the rigid boundary is most violent. The relationship between the velocity of the bubble collapse and its microjet near a rigid boundary is finally described.
Part of the book: Cavitation