Acoustic Wave Problems

The results presented in this book could be of interest to readers from two aspects. Firstly, the possibility of significant expansion of the number of problems allowing the construction of full analytical representations for sound fields in the areas of complex shape was shown. The concept of the general solution of the boundary problem was formulated and its efficiency in solving different tasks was demonstrated. The second distinctive feature of the book is that considerable attention is paid to the analysis of the physical features of sound fields and their relation to the geometrical and physical aspects of acoustic radiators and acoustic caterers. Harmonic sound fields are considered in most cases. However, the possibility to find a solution to nonstationary problems was shown in several problems. There are seven chapters in the book. The first chapter provides the fundamentals of the method of constructing the general solution to boundary problems of classical acoustics. The ways of implementing the proposed method are illustrated by specific examples. This method can be generalised to analyse the fields of different physical nature. The second chapter is devoted to the problem of sound radiation. The fundamental problem of the finite cylinder radiation is considered in depth. The different types of multi-element piezoceramic radiators are discussed and the interaction effects are described considering the properties of electric generators. The third chapter studies the sound scattering by infinite gratings made of elastic shells. Such gratings allow tackling the task of creating a hydro-acoustic sound barrier that is transparent to the flow and non-transparent to the sound. The gratings with piezoceramic active elastic plates is investigated. The fourth chapter examines several problems of diffraction on complex bodies, namely: a partially sound transparent paraboloid reflector, a finite wedge. The problem of sound scattering by a wedge with a given radius of the wedge edge is presented. The fifth chapter focuses on the investigation of the acoustic properties of sound barriers. The classical sound barrier and V-barrier are considered. Noise-reducing properties of the barriers located along city streets were studied. The sixth chapter examines sound propagation features in the human respiratory system. Basing on a spectrum and multifractal analysis, it was concluded that vesicular respiration and bronchial respiration are of different natures. The seventh chapter examines the sound propagation in irregular waveguides, namely: a waveguide with a bend and an elastic cylindrical waveguide filled with liquid.