Research On Interface States In Quasi-one-dimensional Surface Water Wave System

The increased demand for electricity is driving the development of technologies for the exploitation of marine electrical resources.As a kind of marine electrical resource,wave energy is mainly concentrated in the surface layer of seawater.Therefore,the regulation of surface water waves has become a hot spot of attention for scholars in the field of marine engineering.At present,a variety of devices with sensing,focusing,and filtering functions have been realized by using classical wave interface states.In this paper,the concept of classical wave interface state is introduced to a quasi-one-dimensional surface water wave system,which consists of a channel with a periodic sidewall undulation structure.The surface water wave interface states are excited by connecting quasi-one-dimensional periodic channel structures with different physical properties to form heterojunctions.The localization property of the interface states can converge the energy of surface water waves near the heterojunction interface and facilitate wave energy generation.Since the fluctuation equation is universal,this method of excitation of interface states also provides a reference for the design of interface state devices in acoustic and photonic systems.In this paper,the interface states are excited using topological energy bands,higher-order modes,and topological optimization.The specific contents are as follows:1.Topological interface states are excited in a quasi-one-dimensional surface water wave system.In this paper,periodic channel structures with different geometrical characteristics are connected to form a heterojunction,and the properties of surface water wave topological interface states are investigated theoretically and experimentally.The results show that only heterojunctions composed of channels with different topological phase band gaps can excite topological interface states.The surface water wave topological interface states are characterized by anomalous transmission in the Bragg forbidden band and enhanced surface water wave amplitude at the interface of the heterojunction.2.The properties of surface water wave interface states induced by high-order modes are investigated.The spatial symmetry-breaking mechanism is used to make the resonance between the fundamental mode and the high-order modes form the non-Bragg band gap.The results show that the channels generating the non-Bragg band gap are connected to the channels generating the Bragg band gap and the non-Bragg band gap,respectively,and both can excite the surface water wave interface states with the characteristics of high-order modes.Compared with the topological interface state,the surface water wave amplitude of the high-order mode interface state is larger and the localization area is smaller,which is more favorable for the convergence of water wave energy.The frequency of the interface state in the forbidden zone is also adjusted by adjusting the connection phase of the channel.3.The heterojunction channels are designed based on a topology optimization algorithm to excite the interface states with the desired characteristics.A structure matrix is used to describe the gridded channel structure cells,and the transmission spectrum of the heterojunction channel structure is used as the target feature to construct the objective function with added constraints.Genetic algorithms are used to design surface water wave heterojunction channels that can excite the desired interface states.During topology optimization,the channel structure units spontaneously generate topological phase transitions,which in turn excite topological interface states.