Nonlinear property of slightly compressible media permeated with air-filled bubbles

Abstract

Based on the nonlinear oscillation of an airfilled bubble in weakly compressible media at prestressed state, the effective medium method is used to study the nonlinear property of the slightly compressible media permeated with air bubbles. It is this nonlinear oscillation of air bubbles that results in the nonlinear property of the porous media. Numerical results have confirmed that the nonlinearity of the porous media is usually high, though the optimal porosity is very small. Moreover, the nonlinear property is greatly affected by the prestressed state, porosity, and shear modulus of the matrix media.Keywords slightly compressible media, porous media, effective medium method, nonlinear parameter PACS numbers 43.25.Dc, 43.25.Yw ½ ÁÒØÖÓ Ù Ø ÓÒBecause the elastic and viscoelastic materials permeated with air-filled bubbles are used in a large variety of physical situations, it is very important to determine the acoustic properties of porous media. The effective medium theory (EMT) based on resonance scattering theory can be used to obtain the linear acoustic property of porous media [1,2]. However, the nonlinear property of the porous media cannot be obtained by the EMT. The nonlinear acoustic property is very impor-