NONLINEAR RADIATION OF A PLANE CIRCULAR SOUND SOURCE

This study deals with acoustic sources whose radiations in strong field areas are like those of a Gaussian source. A family of such sources is defined. Non-linear effects relative to these sources can be described by those caused by a Gaussian source. An approximate solution in the non-thermoviscous case is studied for a monochromatic source. The field is expressed by several terms. The first term, where special curvilinear coordinates are used, accounts for most of the non-linear effects without any approximation and is of the Fubini type. The following terms, which appear to be corrective terms and depend on curvilinear coordinates also, are solutions of linearized first order partial differential equations. An accurate derivation which leads to numerical applications is made for the first three harmonics. Some results are obtained from a bichromatic source and permits the estimation of the parametric emission up to the shock wave front. In the fluid domain, it is established that the second order approximation is still valid. Directivities and fields on the axis are derived.