Numrical Simulation of Nonlinear Focused Ultrasound

Numerical simulation is employed to characterize the sound field of high intensity focused ultrasound, whose results agree well with the analytical results. The sound field in nonlinear case seems to be much more complicated compared with that in linear case. The first three harmonics are extracted from the distorted wave by the zero-phase band-pass filter. It is demonstrated that the amplitude distribution of fundamental wave change little while that of the second and third harmonics vary a lot, as the source pressure increases. And the relative phase almost keep the same in the focal region. It can be concluded that numerical simulation is of great importance in predicting the nonlinear focused sound field at high sound pressure levels.