Numerical simulation of the acoustic nonlinearity of an orifice

An axisymmetric discrete vortex model is developed in this paper in an attempt to give more understanding of the acoustic nonlinearity of an orifice. First, the vortex shedding process produced by high-amplitude incident sound is numerically simulated. Furthermore, the time history and spectrum of the average flow velocity through an orifice are computed, from which the nonlinear distortion of flow velocity is analyzed. Finally, an effort is made to give prediction of the nonlinear acoustic impedance over a large range of the sound pressure amplitude. One advantage of the present model is in the prediction of the nonlinear acoustic reactance, which is not well solved in the previous quasi-steady models.