Finite Element Modeling Of Microbubble Interactions And Cavitation Behaviors

Ultrasound Contrast Agent (UCA) and Extracorporeal Shock Wave Treatment (ESWT) are both related to acoustic cavitations. In this work, some models were developed based on Finite Element Method (FEM) to simulate the bubble interactions and acoustic cavitation behaviors. Two series of studies were performed as follows:(1) In order to investigate the encapsulated microbubbles dynamics, a FEM model was developed based on fluid mechanics to simulate the dynamic responses of two interacting encapsulating bubbles and the surrounding fluid velocity field. And then the impacts of microbubble parameters (e.g., bubble size, shell elasticity and viscosity) on the bubble dynamics responses and the fluid velocity distribution were thoroughly analyzed based on the FEM simulations.(2) In order to investigate how the shock wave (SW) field would change if a bony structure exists in the path of the acoustic wave. A FEM model was developed based on linear elasticity and acoustic propagation equations to examine SW propagation and deflection near a mimic musculoskeletal bone. High-speed photography experiments were performed to record cavitation bubbles generated in SW field with the presence of mimic bone. By comparing experimental and simulated results, the effectiveness of FEM model was verified and strain energy distributions in the bone were also predicted according to numerical simulations.The results of the current work indicate that, based on appropriate physical theory, FEM method can be used as a useful tool to simulate and analyze the complicated dynamic behaviors of the encapsulated microbubble, which is important for better understanding the mechanisms involved in UCA-assisted diagnostic/therapeutic applications. It is also beneficial for standardizing the treatment dosage, optimizing treatment protocols, and even providing patient-specific treatment guidance in clinic.