Physical modeling of nonlinear sound wave propagation in oceanic waveguides of variable depth

Results of laboratory experiments aimed at studying the spatial distribution of the difference-frequency acoustic wave field in a shallow-water waveguide with a sloping bottom are presented. It is shown that, in an inhomogeneous waveguide, the direction toward the radiation maximum in the angular spectrum of the low-frequency wave continuously varies as the rib of the wedge is approached, whereas, in a homogeneous waveguide, the angular spectrum is shaped. A spatial filtering of low-frequency modes produced by a parametric radiator and reflected from the coastal wedge is experimentally realized. The results of the experiment are confirmed by numerical modeling. Problems of the physical adequacy of the experimental results obtained under actual and laboratory conditions are discussed.