Research On The Influence Of Moving Medium On The Nonlinear Effect Of Sound Wave

With the practical application of nonlinear acoustics,the research of nonlinear acoustics theory is more in-depth study.As everyone knows that the propagation of sound needs media.And most of the media in the nature are moving media,such as flowing air,sea water,etc.It is necessary to consider the impact of the moving medium in the practical application of nonlinear acoustic theory.This paper studies the nonlinear acoustic in moving medium based on the assumption that the medium has uniform velocity.The nonlinear acoustic wave equation in moving medium is derived from the basic equations of fluid dynamics.This paper uses the finite-difference time-domain(FDTD)algorithm to discretize the wave equation,and obtains the differencing scheme of acoustic wave equation in moving medium.Then this paper analyzes the stability and convergence condition of the differencing scheme.In this paper,the propagation of finite amplitude wave and the interaction between two waves are studied.This paper discusses the influence of absorption effect on the nonlinear effect and compares the pressure of higher harmonic in static medium and moving medium.For the interaction between two waves,this paper discusses the influence of the frequency on difference-frequency wave and sum-frequency wave.Then this paper analyses the characteristics of difference-frequency wave in moving medium.