Vortex Field Regulation And Underwater Low-Frequency Sound Insulation Based On Acoustic Artificial Structure

In recent years,the use of artificial structures to manipulate sound waves has become a hotspot in condensed matter physics research.New acoustic devices based on artificial structure theory have continued to emerge,playing an important role in the development of acoustics and showing their unique application potential.This article first introduces recent scientific research progress and cutting-edge theories.The acoustic metasurface designed with five-mode materials introduces orbital angular momentum into underwater acoustic communication.An acoustic waveguide filled with zero-refractive index material was designed to demonstrate the "tunneling effect" of acoustic waves.Explore the realization of multiplex communication of acoustic orbital angular momentum in the field of elastic waves.Combining the idea of gradient control,a class of local resonance type phononic crystal was designed,and its superiority for underwater low-frequency sound insulation was demonstrated.In the second chapter,based on the generalized Snell’s law,an acoustic metasurface is designed using five-mode materials,and the theoretical calculation and parameter distribution of metasurface design are explored.Demonstrate the basic theories and technical methods for generating acoustic orbital angular momentum underwater.In addition,the acoustic orbital angular momentum was introduced into underwater communication,and underwater signal multiplexing was realized by using it.The simulation results confirmed the feasibility of using acoustic orbital angular momentum to realize underwater signal multiplexing.In the third chapter,a phononic crystal with zero refractive index effect is designed.Under the protection of high symmetry,the Dirac-like point is generated in the center of the simplest Brillouin zone by inducing degeneracy.The study found that the effective density and compressive modulus near this type of Dirac frequency are zero.An acoustic waveguide was designed using this phononic crystal,demonstrating that the “tunneling effect” of the acoustic wave in the waveguide can make the acoustic vortex wave stable during the bending transmission process.The waveguide design controls the acoustic vortex field in three-dimensional space.Has guiding significance.In the fourth chapter,the feasibility of using the active phased array method to transmit information in solids using acoustic vortices is explored,and 16 transducers are used to form an array to generate acoustic vortices.Derive the method of realizing acoustic vortex multiplexing and demultiplexing in the solid,design the simulation experiment of realizing the acoustic vortex transmission in the solid,and adopt the technical means such as method coding and decoding based on orthogonal basis.The simulation shows that it is feasible to realize multiplexed acoustic communication in the solid.In the last chapter,based on the principle of local resonance,a three-element threecomponent local resonance phononic crystal is proposed.The sound insulation method is designed with a gradient thinking,and the sound insulation capacity is achieved through the realization of the 200-250 Hz frequency band under water10 d B effect.The results show that the gradient type local resonance phononic crystal has certain advantages in underwater sound insulation applications.