Modelling laser-fluid coupling and cavitation in laser lithotripsy

Abstract

The absorption of laser by fluid and the resulting vapor bubbles plays a significant role in laser lithotripsy and many other industrial applications. In this talk, we present a coupled photo-thermal-mechanical model of laser interaction in compressible multiphase fluid flows. The model couples the three-dimensional compressible Navier–Stokes equation with a nonlocal laser absorption equation. The computational framework is an extension of the recently developed FIVER (“a Finite Volume method with Exact multi-material Riemann solver”) framework, which features the use of level set and embedded boundary methods for tracking material (fluid–fluid and fluid–solid) interfaces, and the solution of local, one-dimensional multi-material Riemann problems for enforcing interface conditions. We will start with a brief review of the key model equations and numerical algorithms adopted by FIVER, as well as recent efforts on verification and validation. Next, physical models of laser absorption and laser-induced heating will be presented. Numerical models and methods for simulating phase change and tracking the vapor–liquid interface will be introduced and assessed. The performance of this computational framework will be demonstrated using several simplified model problems and a numerical experiment of cavitation in Holmium:YAG laser lithotripsy.