Propagation Characteristics of Low Frequency Sound Energy in Range-Dependent Shallow Water Waveguides

Abstract

In view of the low-frequency sound energy propagation in range-dependent waveguides in shallow water, in cylindrical coordinates, the sound energy flux is used as the study object based on the finite element method (FEM). The influence laws and the corresponding mechanisms of three types of complex seabed topographies, wedye-shaped seabed, seamount, and trench on sound energy propagation characteristics in sound field are discussed combined with specific simulation examples. The simulation results reveal that the FEM can accurately calculate sound field distribution in any seabed topography. For the up-sloping wedge-shaped seabed, the greater the inclination angle is, the stronger the sound energy leaks to the bottom, the more rapid the sound energy attenuates in water. But for the down-sloping wedge-shaped seabed the opposite is true. A small seamount enhances the sound energy above it, but hinders the reception of the sound energy behind it. The influence laws of small trenches are related to the grazing angle of sound energy. Only when the horizontal angle of the trench is smaller than the grazing angle of each normal mode in waveguide, would the sound energy be influenced in propagation.

Keywords

• shallow water waveguides
• low frequency
• finite element method (fem)
• sound energy flux