Cylindrical Acoustic Waves Research Articles

Experimental Study on Underwater Cylindrical Acoustic Wave Generated by High-Voltage Pulse Excited Cable

Experimental Study on Underwater Cylindrical Acoustic Wave Generated by High-Voltage Pulse Excited Cable

Influence of Homo- and Hetero-Junctions on the Propagation Characteristics of Radially Propagated Cylindrical Surface Acoustic Waves in a Piezoelectric Semiconductor Semi-Infinite Medium

This paper theoretically investigates the influence of homo- and hetero-junctions on the propagation characteristics of radially propagated cylindrical surface acoustic waves in a piezoelectric semiconductor semi-infinite medium. First, the basic equations of the piezoelectric semiconductor semi-infinite medium are mathematically derived. Then, based on these basic equations and the transfer matrix method, two equivalent mathematical models are established concerning the propagation of radially propagated cylindrical surface acoustic waves in this piezoelectric semiconductor semi-infinite medium. Based on the surface and interface effect theory, the homo- or hetero-junction is theoretically treated as a two-dimensional electrically imperfect interface in the first mathematical model. To legitimately confirm the interface characteristic lengths that appear in the electrically imperfect interface conditions, the homo- or hetero-junction is equivalently treated as a functional gradient thin layer in the second mathematical model. Finally, based on these two mathematical models, the dispersion and attenuation curves of radially propagated cylindrical surface acoustic waves are numerically calculated to discuss the influence of the homo- and hetero-junctions on the dispersion and attenuation characteristics of radially propagated cylindrical surface acoustic waves. The interface characteristic lengths are legitimately confirmed through the comparison of dispersion and attenuation curves calculated using the two equivalent mathematical models. As piezoelectric semiconductor energy harvesters usually work under elastic deformation, the establishment of mathematical models and the revelation of physical mechanisms are both fundamental to the analysis and optimization of micro-scale surface acoustic wave resonators, energy harvesters, and acoustic wave amplification based on the propagation of surface acoustic waves.

Acoustic stability of a self-gravitating cylinder leading to astrostructure formation

We employ a quantum hydrodynamic model to investigate the cylindrical acoustic waves excitable in a gyromagnetoactive self-gravitating viscous cylinder comprised of two-component (electron–ion) plasma. The electronic equation of state incorporates the effect of temperature degeneracy. It reveals an expression for the generalized pressure capable of reproducing a completely degenerate (CD) quantum (Fermi) pressure and a completely non-degenerate (CND) classical (thermal) pressure. A standard cylindrical wave analysis, moderated by the Hankel function, yields a generalized linear (sextic) dispersion relation. The low-frequency analysis is carried out procedurally in four distinct parametric special cases of astronomical importance. It includes the quantum (CD) non-planar (cylindrical), quantum (CD) planar, classical (CND) non-planar (cylindrical), and classical (CND) planar. We examine the multi-parametric influences on the instability dynamics, such as the plasma equilibrium concentration, kinematic viscosity, and so forth. It is found that, in the quantum regime, the concentration plays a major role in the system destabilization. In the classical regime, the plasma temperature plays an important role in both the stabilization and destabilization. It is further seen that the embedded magnetic field influences the instability growth dynamics in different multiparametric regimes extensively, and so forth. The presented analysis can hopefully be applicable to understand the cylindrical acoustic wave dynamics leading actively to the formation of astrophysical gyromagnetic (filamentary) structures in diverse astronomical circumstances in both the classical and quantum regimes of astronomical relevance.

Inward and outward dust acoustic cylindrical and spherical waves interaction in four-component dusty plasma with nonthermal ions

Abstract A theoretical investigation by an all-inclusive adaptation of the PLK strategy is carried out in order to study the inward and outward interaction between two cylindrical and spherical dust acoustic solitary waves (DASWs) in an unmagnetized dusty plasma consisting of nonthermal distributed ions, negatively and positively charged dust grains along with electrons featuring Boltzmann’s distribution. The interactions and collisions between two cylindrical and spherical geometries at different time scales are studied. Also the combined effects of the nonthermality of ions, ion to electron temperature ratio as well as mass ratio of positive to negative dust grains have been studied in detail on the phase shifts raised due to collision. It has been seen that the properties of the cooperation of DASWs in cylindrical and spherical shaped are distinct.

Analysis of SH wave in hollow piezo-composite cylinder with coupled imperfect interface condition

Present study primarily focuses on interpreting the propagation pattern of Shear horizontal (SH) wave in a piezo-composite layered cylinder. The structure consists of three concentric cylinders composed of hollow fiber-reinforced (FR) cylinder enclosed within piezomagnetic (PM) cylinder along the curved surface area which is similarly superimposed by a piezoelectric (PE) cylinder. The overall system is believed to be pre-stressed in a circumferential direction. The common boundary between each of the cylinder is demonstrated as imperfectly bonded. At the interface of PM and PE media, mechanical, electrical, magnetic and inter-coupled types of imperfections are assumed. Dispersion relations have been obtained for both the electrically open magnetically short (EOMS) and electrically short magnetically open (ESMO) circuit condition. Dispersion curves have been plotted to unravel the peculiarities of parameters like the radius of the hollow cylinder, thickness of FR and PM cylinder, thickness ratio of PM and PE cylinder, initial stress parameters, helical angle of the reinforcement. The influence of different interface parameters on the phase velocity of the wave has been studied and marked distinctly. For a detailed study, two successive modes have been plotted. Present study may help in improving the performance of piezo-composite cylindrical surface acoustic wave (SAW) sensors.

Cylindrical and Spherical Dust-Ion Acoustic Solitary Waves by Damped Korteweg-de Vries-Burgers Equation

Theoretical investigations are carried out for the cylindrical and spherical dust-ion acoustic solitary waves with the kinematic viscosity. By the reductive perturbation technique the damped KdV-Burgers equation is obtained, and an approximate analytical solution is given. Using this solution, the effects of different physical parameters on dust-ion acoustic solitary wave are discussed. The results may have applications in laboratory and space plasmas.

Particle acceleration by ion-acoustic solitons in plasma

We propose a new acceleration mechanism for charged particles by using cylindrical or spherical non-linear acoustic waves propagating in ion-electron plasma. The acoustic wave, which is described by the cylindrical or spherical Kortweg-de Vries equation, grows in its wave height as the wave shrinks to the center. Charged particles confined by the electric potential accompanied with the shrinking wave get energy by repetition of reflections. We obtain power law spectrums of energy for accelerated particles. As an application, we discuss briefly that high energy particles coming from the Sun are produced by the present mechanism.

Thermoacoustic-reflected focusing lens based on acoustic Bessel-like beam with phase manipulation**Project supported by the National Natural Science Foundation of China (Grant Nos. 11774137 and 51779107), the Six-Talent Peaks Project in Jiangsu Province, China (Grant No. GDZB-019), the China Postdoctoral Science Foundation (Grant No. 2017M621643), the Natural Science Foundation of Jiangsu Higher Educational Institutions of China (Grant No. 18KJB140003), and the

We report the realization of broadband reflected acoustic focusing lenses based on thermoacoustic phased arrays of Bessel-like beams, in which the units of phase manipulation are composed of three rigid insulated boundaries and a thermal insulation film in air with different temperatures. Based on these units, we realize a reflected focusing lens which can focus reflected acoustic energy on a line, and its fractional bandwidth can reach about 0.29. In addition, we discuss the influences of the base angle of Bessel-like beam, the number of basic unit, and the variation of unit temperature on focusing performances in details. Furthermore, the reflected focusing lens for the cylindrical acoustic wave based on the Bessel-like beam is also demonstrated. The proposed focusing lens has the advantages of a broad working bandwidth, large focus size, and high robustness, which may provide possibilities for the design and application of acoustic lenses.

On the Regular Integral Solutions of a Generalized Bessel Differential Equation

The original Bessel differential equation that describes, among many others, cylindrical acoustic or vortical waves, is a particular case of zero degree of the generalized Bessel differential equation that describes coupled acoustic-vortical waves. The solutions of the generalized Bessel differential equation are obtained for all possible combinations of the two complex parameters, order and degree, and finite complex variable, as Frobenius-Fuchs series around the regular singularity at the origin; the series converge in the whole complex plane of the variable, except for the point-at-infinity, that is, the only other singularity of the differential equation. The regular integral solutions of the first and second kinds lead, respectively, to the generalized Bessel and Neumann functions; these reduce to the original Bessel and Neumann functions for zero degree and have alternative expressions for nonzero degree.

On the extension of cylindrical acoustic waves to acoustic-vortical-entropy waves in a flow with rigid body swirl

The noise of jet and rocket engines involves the coupling of sound to swirling flows and to heat exchanges leading in the more complex cases of triple interactions to acoustic-vortical-entropy (AVE) waves. The present paper presents the derivation of the AVE equation for axisymmetric linear non-dissipative, compressible perturbations of a non-homentropic, swirling mean flow, with constant axial velocity and constant angular velocity for a perfect gas with constant density. The axisymmetric AVE wave equation is obtained for the radial velocity perturbation, specifying its radial dependence for any frequency and axial wavenumber. The AVE wave equation in the case of zero axial wavenumber, corresponding to cylindrical AVE waves, has no singularities for finite radius, including the sonic radius, where the isothermal Mach number for the swirl velocity is unity. The exact solution of the AVE wave equation for the fundamental axisymmetric mode with zero axial wavenumber is obtained without any restriction on frequency, as series expansions of Gaussian hypergeometric type: (i) covering the whole flow region; (ii) specifying the wave field at the sonic radius; (iii) specifying near-axis and asymptotic scaling for small and large radius. Using polarization relations among wave variables specifies exactly and allows the plotting of the perturbations of: (i,ii) the radial and azimuthal velocity; (iii,iv) pressure and mass density; (v,vi) entropy and temperature. Thus the extension of cylindrical acoustic waves, that are specified by Bessel functions, to cylindrical acoustic-vortical-entropy waves, is specified by Gaussian hypergeometric functions.

Acoustic focusing lens with near-zero refractive index based on coiling-up space structure

An acoustic focusing lens based on a coiling-up space structure with near-zero refractive index is studied. According to the direction selection mechanism for acoustic waves in a near-zero refractive index material, we adopt the coiling-up space structure as a basic unit for arrangement, and design a geometric structure with specific incident and outgoing interfaces which is used to manipulate the outgoing direction of transmitted wave. Thus, the focusing effects for plane acoustic wave and cylindrical acoustic wave are realized. Besides, the influences of rigid scatterers inside the lens on the focusing performance are also discussed in detail. Moreover, the shape and direction of the acoustic waveform can be manipulated accurately by changing the outgoing interface of the lens with the near-zero refractive index. The results show that the lens with a single and two circular surfaces could realize the focusing effects of the plane and cylindrical acoustic waves, respectively, and the rigid scatterers inside the lens have no effects on the focusing performance. In addition, the cylindrical acoustic wave could be transformed into the plane acoustic wave through the lens with the circular incident surface and the plane exit surface, and the inclined angle of the exit surface could be used to manipulate the propagation direction of the plane wave. The simulation results between the lenses composed of the coiling-up space structure and the effective medium are in good agreement with each other. This type of lens has the advantages of single cell structure, high focusing performance, and high robustness. This work provides theoretical guidance and experimental reference for designing a novel acoustic focusing lens with the near-zero refractive index, and offers a new idea for studying the manipulation of the acoustic waveforms.

Propagation of cylindrical acoustic waves in dusty plasma with positive dust

The hydrodynamic equations of positive and negative dust, Boltzmann electron and ion density distribution, and Poisson equation are used along with the reductive perturbation method to derive a cylindrical Kadomtsev-Petviashvili (CKP) equation. G′/G expansion method is used to obtain a new class of solutions. At certain condition, the solutions degenerate to solitary wave solutions. The effects of the physical parameters on the characteristics of solitary pulses are examined. The results give elucidation of the properties of dust acoustic solitary pulses in multicomponent space plasmas, particularly in interstellar dust clouds in a galactic disk and astrophysical plasma systems.

Time evolution of nonplanar electron acoustic shock waves in a plasma with superthermal electrons

The propagation of cylindrical and spherical electron acoustic (EA) shock waves in unmagnetized plasmas consisting of cold fluid electrons, hot electrons obeying a superthermal distribution and stationary ions, has been investigated. The standard reductive perturbation method (RPM) has been employed to derive the cylindrical/spherical Korteweg-de-Vries-Burger (KdVB) equation which governs the dynamics of the EA shock structures. The effects of nonplanar geometry, plasma kinematic viscosity and electron suprathermality on the temporal evolution of the cylindrical and spherical EA shock waves are numerically examined.

Nonplanar electron acoustic shock waves

The properties of cylindrical and spherical electron acoustic shock waves (EASWs) in an unmagnetized plasma consisting of cold electrons, immobile ions and Boltzmann distributed hot electrons are investigated by employing the reductive perturbation method. A Korteweg–de Vries Burgers (KdVB) equation is derived and its numerical solution is obtained. The effects of several parameters and ion kinematic viscosity on the basic features of EA shock waves are discussed in nonplanar geometry. It is found that nonplanar EA shock waves behave quite differently from their one-dimensional planar counterpart.

A note on acoustic diffraction by an absorbing finite strip in a moving fluid

The problem of cylindrical acoustic wave diffraction from an absorbing finite barrier in a moving fluid has been investigated in an improved form. The diffracted field in the far zone has already been discussed in [1], but due to some mathematical complications, the absorbing parameter was ignored in that study. In the present analysis, the absorbing parameter is taken into account up to order one and presented in a better form solution. Moreover, the solution obtained in this analysis can be used to recover the results for the case of semi-infinite barrier [2] by taking an appropriate limit l → ∞. The results for still fluid can also be gathered by taking the value of Mach number to be zero. The integral transforms, Wiener-Hopf techniques and asymptotic expansions are used to acquire the diffracted field in the far zone. Finally, the solution is well supported by the graphical results showing the effects of various physical parameters on the separated field.

Effects of an Electric Field on the Cylindrical Dust Acoustic Wave in Magnetized Complex Plasmas

Stability of a dust acoustic wave in cylindrical complex plasmas is investigated. Effects of a static magnetic field (axial) and an electric field (radial) on the propagation of a low frequency wave are studied. The linear dispersion relations of rotational modes and breathing modes are derived. When a dusty plasma is confined in a finite region, the void behavior is observed at high speed rotation. Vivid structures of different-mode-number solutions are illustrated.

Nonplanar electron acoustic shock waves in a plasma with electrons featuring Tsallis distribution

The properties of cylindrical and spherical electron acoustic shock waves (EASWs) in an unmagnetized plasma consisting of cold electrons, immobile ions, and hot electrons featuring Tsallis statistics are investigated by employing the reductive perturbation technique. A Korteweg-de Vries Burgers (KdVB) equation is derived and its numerical solution is obtained. The effects of electron nonextensivity and electron kinematic viscosity on the basic features of EA shock waves are discussed in nonplanar geometry. It is found that nonextensive nonplanar EA shock waves behave quite differently from their planar counterpart. Deviations from a pure planar geometry are significant only for times shorter that the inverse of the cold electron plasma frequency. Given that the hot electron dynamics is the most interesting one, and that in many astrophysical scenarios the cold electrons can be significantly rarefied, this restriction is not too limiting for the applicability of our model.

Cylindrical and spherical electron acoustic solitary waves in the presence of superthermal hot electrons

Propagation of cylindrical and spherical electron-acoustic solitary waves in unmagnetized plasmas consisting of cold electron fluid, hot electrons obeying a superthermal distribution and stationary ions are investigated. The standard reductive perturbation method is employed to derive the cylindrical/spherical Korteweg-de-Vries equation which governs the dynamics of electron-acoustic solitons. The effects of nonplanar geometry and superthermal hot electrons on the behavior of cylindrical and spherical electron acoustic soliton and its structure are also studied using numerical simulations.

Cylindrical and spherical electron acoustic solitary waves with nonextensive hot electrons

Nonlinear propagation of cylindrical and spherical electron-acoustic solitons in an unmagnetized plasma consisting cold electron fluid, hot electrons obeying a nonextensive distribution and stationary ions, are investigated. For this purpose, the standard reductive perturbation method is employed to derive the cylindrical/spherical Korteweg-de-Vries equation, which governs the dynamics of electron-acoustic solitons. The effects of nonplanar geometry and nonextensive hot electrons on the behavior of cylindrical and spherical electron acoustic solitons are also studied by numerical simulations.

Cylindrical and spherical dust acoustic solitary waves in dusty plasma with superthermal ions and electrons

Nonlinear propagation of cylindrical and spherical dust-acoustic solitons in an unmagnetized dusty plasma consisting of cold dust grains, superthermal ions and electrons are investigated. For this purpose, the standard reductive perturbation method is employed to derive the cylindrical/spherical Korteweg-de-Vries equation which governs the dynamics of dust-acoustic solitons. The effects of nonplanar geometry and superthermal distributions on the cylindrical and spherical dust acoustic solitons structures are also studied by numerical calculation of the cylindrical/spherical Korteweg-de-Vries equation.