Nagayoshi Morita

Finite difference time domain simulation of nonlinear ultrasonic pulse propagation

The extracorporeal shock wave lithotripsy has come into wide use rapidly owing to its advantage of non‐invasiveness. However, as for the shock wave propagation in the human body in relation to practical lithotripsy, reports of numerical simulation based on models conforming to a practical situation are very few. In this paper, excited pulse wave forms are measured by using a water tank model based on a practical lithotriptor and numerical simulation is made on the basis of these measured data. A new FDTD algorithm is proposed and used for this simulation, the problem being connected with extracorporeal shock wave lithotripsy. In this simulation method, conventional plane wave approximation is not used but original equations including convection terms are directly employed to derive new FDTD algorithms. This method is applied to an experimental setup and its numerical model that resemble an actual treatment situation to compare sound pressure distributions obtained numerically with those obtained experimen...