THREE TIME-DOMAIN COMPUTATIONAL MODELS FOR QUASI-STANDING NONLINEAR ACOUSTIC WAVES, INCLUDING HEAT PRODUCTION

Abstract

Applications of high-amplitude acoustic or ultrasonic waves in industrial processing require a good knowledge of the nonlinear pressure field, as well as the heat produced by the wave. In this article a new time-domain algorithm solving a second-order nonlinear wave equation written in Lagrangian coordinates and valid for any fluid is presented. The new model is compared with two others which were previously developed, corresponding to the two other possible physical approaches. This paper discusses the limits of application of every approach and the suitability of every one to model nonlinear acoustic waves in resonators. Conclusions about the applicability of the physical models are given. The time-domain character of the models allows the development of a new algorithm to calculate the temperature evolution inside a resonator due to acoustic losses. This algorithm is presented here and applied to strongly nonlinear waves for which the nonlinear attenuation is dominant. Several kinds of time functions for excitation can be considered in the models. The strongly nonlinear resonator response to a short pulsed signal is analyzed to show the efficiency of the time-domain numerical model.