Scholte waves at the seafloor have significant potential for underwater detection and communication, so a study about detecting Scholte waves is very meaningful in practice. In this paper, the detection of Scholte waves at the seafloor is researched theoretically and experimentally. Acoustic models with the multilayer elastic bottom are established according to the ocean environment, and a tank experiment is designed and carried out to detect Scholte waves. Different from detecting Scholte waves in the seismic wavefield, a technique for detecting Scholte waves in the sound pressure field is proposed in this paper. The experimental results show that the proposed technique can detect Scholte waves effectively, and there are no problems such as seabed coupling and the effect of wave speeds. Furthermore, the results also show that this detection technique is still effective in conditions with a sediment layer. The existence of sediment layers changes the acoustic field conditions and affects the excitation of Scholte waves.

High order Bragg scattering from sand ripples is investigated by a tank experiment, where the artificially produced sand ripples have a spatial period of 0.2 m and ripple height of 5 cm. Bragg scattering has been measured at three frequencies 22 kHz, 24.57 kHz, and 27 kHz and three incident grazing angles 20∘, 30∘, 40∘ by a method based on the conventional beamforming using two horizontal receiving arrays. It is illustrated that high order Bragg scatterings can be observed, and the corresponding scattered grazing angles agree with the theoretical prediction. Owing to the ripple height being on the order of wavelength, it is found that the distribution of forward scattering amplitude is different from the distribution for sand ripples of small height, i.e., the diffuseness of scattering amplitude is increased with the ripple height.

In this paper, an elastic seafloor with the sinusoidal interface is modeled to study the effect of the fluctuant interface on Scholte wave excitation. The reflection and transmission coefficients of sound waves are derived from the scattered wave theory to investigate the acoustic field characteristics. In numerical simulations, longitudinally invariant finite element models are constructed to demonstrate the excitation of Scholte waves at the seafloor. The effect of sinusoidal interface parameters on Scholte wave excitation is analyzed in this research. Results show that stronger Scholte waves still can be excited when the sound source is away from the seafloor with a sinusoidal interface. In this process of Scholte wave excitation, the period [Formula: see text] and height [Formula: see text] of sinusoidal interfaces are related to the excitation frequency and intensity, respectively.