Numerical Study On Sound Propagation In Flexible Channel Via Lattice Boltzmann Method

The propagation of sound waves on the flexible boundary is not only widely exist in nature,but also has a very important application in engineering,such as the propagation of sound waves in the bottom of the sea,sound absorption of the flexible porous medium materials,so people pay more and more attentions to the propagation of sound waves on the flexible boundary.To study this kind of problem more simply,people usually simplify the sound-wave propagation in porous medium to the channel model.The study of sound-wave propagation in the channel can reflect the basic physic laws,moreover,it makes the research easier.In attention,we considered the sand in the sea has certain flexibility.In order to depict the property of the sound waves in such media more truly,in this paper,we chose the flexible channel model to investigate this problem.The problem of the propagation of sound waves in the flexible channel not only including a lot of disciplines such as acoustics,fluid dynamics,mechanics of elasticity,but also involving the complex fluid-structure interaction surface,so that the study of this problem is not enough.In this paper,we used a mesoscopic method called Multi-Relaxation-Time lattice Boltzmann method to investigate the propagation of sound waves in the flexible channel.We chose the lattice spring model to model the flexible wall,and for the fluid-structure interaction interface,we used the immersed boundary-lattice Boltzmann method to deal with.With the evolution of the fluid,we used the density information which we has obtained to calculate the whole acoustic field.Through the numerical simulation,we obtained that:(1)the effects of the parameters of the flexible wall(Young's modulus,density ratio)and the different fluids in the flexible channel on the sound-wave propagation.When the density ratio of flexible wall is small,the effect of flexible channel on the propagation of sound waves is larger,and when the sound wave frequency is approach to the inherent frequency of the flexible solid,the value of acoustic attenuation has a significantly increased.(2)Compared with the medium is water in the channel,there is little effect on the acoustic attenuation for air.(3)This paper also studied the effects of the flexible channel on different wavelength of sound wave,in terms of overall trend,with the increase of wavelength,the flexible channel makes acoustic attenuation bigger.When ? =170,the acoustic frequency and inherent frequency of the flexible wall is closed,so that the acoustic attenuation is greater.(4)we also simulated the effects of the rubber material on the different wavelength of sound wave.When the medium of the channel is air,the flexible channel has little impact on the wavelength of sound wave,but for the water,the flexible channel has a great effect within certain range wavelength of sound wave.