Propagation of pressure waves inside a confined fluid channel with an irregular floor

The BEM has been used to compute the variations in the pressure field caused when a dilatational point load is placed inside a confined fluid channel. The channel was assumed to be filled with a homogeneous fluid and the presence of irregularities in its floor was considered. The width of the channel was fixed, and the influence of the walls was analyzed. This paper extends previous work by the authors(1,2) in which the fluid channel was considered to have infinite width. The Green's functions are defined in the frequency domain. They are obtained by superposing virtual acoustic sources, combined so as to generate the boundary conditions of both the free surface of the channel and the rigid surfaces of the floor and side walls. The responses in the time domain are obtained by means of Fourier transforms, making use of complex frequencies. The main features and spectral representation of the signals scattered by irregular floors are then described and used to elucidate some important aspects of wave acoustics, which may provide the basis for the development of non-destructive testing and imaging methods.