Energy transfer through boiling-cavitation interaction in high-intensity focused ultrasound

Abstract

The primary mechanism causing energy topological distortion in the target area is the high-order synergy between boiling phase transition and inertial cavitation caused by high-power short-pulse (HPSP) focused ultrasound. A new multi-physics model that links bubble swarms with the thermo-acoustic phase transition at all scales is presented in this research. The pure enthalpy approach is used to objectively quantify a temperature clamping effect (locked at 100±1 ℃) of the latent heat of vaporization (≈ 2.37×10 9 J/m 3 ). The microcompressible Keller-Miksis equation is updated by coupling the elastic deviatoric stress of the fully incompressible solid phase ( υ = 0.5), indicating that the bubble wall collapse Mach number can reach an anomalous breakthrough of 1.2 due to the release of tissue shear elastic energy. The spatiotemporal genesis of the clinical “tadpole-shaped” lesion distortion brought on by bubble cloud shielding is revealed by two-dimensional acoustic field reconstruction. This leads to the proposal of a closed-loop control method with a 20 % dynamic duty cycle. This approach accurately anchors the focal region to the analytical solution (78.4 °C) using thermal relaxation, as confirmed by the construction of a highly sensitive phase transition surrogate model with transient acoustic pressure gating operators. Additionally, it accurately reduces about 99.4 % of unsuccessful mechanical over-kill by displaying the distinct tiny step-like physical fusing features of low-frequency pulses. Intended primarily for medical therapeutic applications, this work establishes a foundation in fluid dynamics and multiphysics mathematical modeling for a novel class of clinical conformal ablation methods by bridging the gap between microscopic dynamics and macroscopic thermal response.