Numerical Computation of Circumferential Waves in Cylindrical Curved Waveguides

We present a complex field general variational statement to study the waves propagating in the circumferential directions of cylindrical curved waveguides. A semi-analytical technique that has been applied on straight waveguides in the literature is reformulated to adapt to the circumferential directions and used for constructing the trial wavefunction in complex field. The method requires the waveguide to be analyzed to be geometrically and physically uniform along its circumferential axis; however, its circumferential cross-section can be arbitrarily complex. The formulation is verified using various examples, which were examined previously by other numerical or analytical solutions. Different cases were studied and comparisons with those published are also performed show the utility and advantages of present method.

Scattering acoustic from one-layered cylindrical shell: Estimation of the radius ratio using reduced cutoff frequencies of circumferential waves

The obtained results from previous studies done in the acoustic scattering of a plane wave by an elastic cylindrical shell, show that the acoustic resonances of a cylindrical shell are related to its physical and geometrical properties. In order to estimate the radius ratio of an airfield immersed cylindrical shell, using reduced cutoff frequencies of circumferential waves that propagate around it. In this work, an approach based on the artificial neural networks was proposed. This approach uses the reduced cutoff frequencies of circumferential waves, extracted using modal isolation plan representation us the analyzing data, in the object to obtain the value of the radius ratio corresponding to the studied cylindrical shell. The proposed approach allows us to estimate accurately the values of the radius ratio of a copper cylindrical shell, and can help us to resolve other problems related to scattering acoustic. Furthermore, it can be used to estimate various parameters of a cylindrical shell starting from the characteristics of which it is disposed. The proposed approach used in this study does not present any approximation as in the case of the natural mode method which assimilate the cylindrical shell to the plate with the same thickness.

Modeling Of Transverse Detonation Waves In A Flat-Radial Annular Channel

Acoustic properties of two regions of gases with different temperatures arising at the initial stage of evolution of transverse detonation waves in annular channel were examined. Mechanics of acoustic vibrations and waves are studied using both numeric and analytical and methods. Rotating circumferential waves at boundary surface of two gases with different temperatures were discovered and rotation velocities of these waves were determined.

Guided Circumferential Waves in Layered Poroelastic Cylinders

The present paper investigates the propagation of time harmonic circumferential waves in a two-dimensional hollow poroelastic cylinder with an inner shaft (shaft-bearing assembly). The hollow poroelastic cylinder and inner shaft are assumed to be infinite in axial direction. The outer surface of the cylinder is stress free and at the interface, between the inner shaft and the outer cylinder, it is assumed to be free sliding and the interfacial shear stresses are zero, also the normal stress and radial displacements are continuous. The frequency equation of guided circumferential waves for a permeable and an impermeable surface is obtained. When the angular wave number vanish the frequency equation of guided circumferential waves for a permeable and an impermeable surface degenerates and the dilatational and shear waves are uncoupled. Shear waves are independent of the nature of surface. The frequency equation of a permeable and an impermeable surface for bore-piston assembly is obtained as a particular case of the model under consideration when the outer radius of the hollow poroelastic cylinder tends to infinity. Results of previous studies are obtained as a particular case of the present study. Nondimensional frequency as a function of wave number is presented graphically for two types of models and discussed. Numerical results show that, in general, the first modes are linear for permeable and impermeable surfaces and the frequency of a permeable surface is more than that of an impermeable surface.