scholarly journals Analytical Investigation of Transient Wave Propagation in One-Dimensional Unsaturated Poroelastic Materials

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Hao Xiong
Keyword(s):  
Wave Propagation ◽  
Dynamic Response ◽  
Fluid Pressure ◽  
Vertical Displacement ◽  
Solid Particles ◽  
Air Pressure ◽  
Transient Wave ◽  
One Dimensional ◽  
Fluid Saturation ◽  
Poroelastic Materials

As a dynamic response, the wave propagation phenomenon usually varies with different media. In this study, the dynamic response of unsaturated poroelastic materials to an impulse load has been analytically investigated. The governing equations, in the Laplace domain, of the unsaturated poroelastic soil in terms of the variables us (solid displacement), pf (pore fluid pressure), and pa (pore air pressure) will be derived. These equations will be simplified in a one-dimensional form. The solutions that include the dynamic response to the vertical displacement of solid particles and to the variations of fluid and air pressures will be provided which are applicable for an arbitrary loading form. The solutions were validated with the results for saturated soil presented in the literature. The effect of material parameters on dynamic response was analysed through a series of parameter studies. It was found that increasing the porosity or fluid saturation effectively increases the amplitude of fluid and air pressures as well as the wave velocity. Although increasing the fluid saturation leads to solid displacement gradually decreases gradually, it results in increasing the amplitude of fluid and air pressure. The fluid saturation increasing above 0.9 results in wave travels faster significantly. The variation of fluid intrinsic permeability has little influence on the soil dynamic response until it reaches a high level. The findings of this study can help for better understanding of one-dimensional wave propagation in unsaturated soil.

Numerical Analysis of Transient Wave Propagation in Nonlinear One-Dimensional Waveguides by Using the Spectral Finite Element Method

2015 ◽  
Vol 10 (5) ◽  
Author(s):  
Yu Liu ◽  
Andrew J. Dick
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wave Propagation ◽  
Geometric Nonlinearity ◽  
Material Nonlinearity ◽  
Transient Wave ◽  
One Dimensional ◽  
Transient Wave Propagation ◽  
1D Model ◽  
Element Method

In this paper, transient wave propagation in nonlinear one-dimensional (1D) waveguides is studied. A complete nonlinear (CN) 1D model accounting for both axial and transverse displacements is developed and geometric and material nonlinearities are separately modeled. The alternating frequency-time finite element method (AFT-FEM) is implemented for this complete 1D model. Numerical simulations are conducted and the response behaviors for axial and transverse motions are analyzed. Comparison of the responses for the geometrically nonlinear (GN) model with a corresponding linear model supports predictions made from the previous analytical studies that the geometric nonlinearity has limited influence on the response of transient transverse waves in the intermediate strain regime. On the contrary, strong nonlinear behavior appears in the response for the materially nonlinear (MN) models. Depending on the local nonlinear property of the material in the intermediate strain regime, the amplitude of the response can be significantly influenced and additional dispersion can be introduced into the response. An exploration of the interaction between the geometric nonlinearity and the material nonlinearity for a rod model in a large strain regime is also conducted and the responses are analyzed by using time-frequency analysis. The competing effect of the geometric nonlinearity and the material nonlinearity can result in a pseudolinear response in a strong nonlinear system for a given range of impact loading.

One-Dimensional Transient Wave Propagation in a Dry Overlying Saturated Ground

2019 ◽  
Vol 23 (10) ◽  
pp. 4297-4310
Author(s):  
Jiang Tao Yi ◽  
Lei Zhang ◽  
Fei Jian Ye ◽  
Siang Huat Goh
Keyword(s):  
Wave Propagation ◽  
Transient Wave ◽  
One Dimensional ◽  
Transient Wave Propagation

Dynamic Response of Two-Dimensional Fluid-Saturated Porous Beam

2014 ◽  
Vol 580-583 ◽  
pp. 169-174 ◽  
Author(s):  
Feng Xi Zhou ◽  
Qiang Ma
Keyword(s):  
Dynamic Response ◽  
Fluid Pressure ◽  
Pore Fluid ◽  
Solid Particles ◽  
Fourier Series Expansion ◽  
Loading Frequency ◽  
Harmonic Load ◽  
Two Dimensional ◽  
Response Characteristics ◽  
Fluid Permeability

The dynamic response of the two dimensional fluid-saturated porous beam has been studied based on the linear elastic theory and the Biot’s model for saturated porous media, in which the compressibility of solid particles and fluid and the viscosity of pore fluid are taken into account. By adopting Fourier series expansion and solving ordinary differential equations, the calculation formula for dynamic response of a two dimensional simply-supported fluid-saturated porous beam is established. The dynamic response characteristics of the forced vibration under uniformly distributed harmonic load are analyzed as a numerical example. Moreover, the solid displacement and pore fluid pressure of the two-dimensional fluid-saturated porous beam would be affected by the surface in filtration conditions, pore fluid permeability coefficient and loading frequency parameters etc.

Nonlinear dynamics of pulsating detonation wave with two-stage chemical kinetics in the shock-attached frame

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Yaroslava E. Poroshyna ◽  
Aleksander I. Lopato ◽  
Pavel S. Utkin
Keyword(s):  
Wave Propagation ◽  
Detonation Wave ◽  
Model Comparison ◽  
Approximation Order ◽  
Transition Regime ◽  
Stage Model ◽  
Two Stage ◽  
One Dimensional ◽  
Kinetics Of ◽  
Detonation Wave Propagation

Abstract The paper contributes to the clarification of the mechanism of one-dimensional pulsating detonation wave propagation for the transition regime with two-scale pulsations. For this purpose, a novel numerical algorithm has been developed for the numerical investigation of the gaseous pulsating detonation wave using the two-stage model of kinetics of chemical reactions in the shock-attached frame. The influence of grid resolution, approximation order and the type of rear boundary conditions on the solution has been studied for four main regimes of detonation wave propagation for this model. Comparison of dynamics of pulsations with results of other authors has been carried out.

scholarly journals Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 443-452
Author(s):  
Tianshu Jiang ◽  
Anan Fang ◽  
Zhao-Qing Zhang ◽  
Che Ting Chan
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Waves ◽  
Anderson Localization ◽  
Random Media ◽  
Normal Incidence ◽  
Disordered Media ◽  
One Dimensional ◽  
Gain Loss ◽  
The Waves ◽  
Localization Behavior

AbstractIt has been shown recently that the backscattering of wave propagation in one-dimensional disordered media can be entirely suppressed for normal incidence by adding sample-specific gain and loss components to the medium. Here, we study the Anderson localization behaviors of electromagnetic waves in such gain-loss balanced random non-Hermitian systems when the waves are obliquely incident on the random media. We also study the case of normal incidence when the sample-specific gain-loss profile is slightly altered so that the Anderson localization occurs. Our results show that the Anderson localization in the non-Hermitian system behaves differently from random Hermitian systems in which the backscattering is suppressed.

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