scholarly journals Reflection of Plane Waves from a Free Surface of an Initially Stressed Transversely Isotropic Dissipative Medium

2011 ◽  
Vol 02 (09) ◽  
pp. 1129-1133 ◽  
Author(s):  
Baljeet Singh ◽  
Jyoti Arora
Keyword(s):  
Free Surface ◽  
Plane Waves ◽  
Transversely Isotropic ◽  
Dissipative Medium

scholarly journals Dispersion equation of Rayleigh waves in transversely isotropic nonlocal piezoelastic solids half-space

2019 ◽  
Vol 41 (4) ◽  
pp. 363-371
Author(s):  
Do Xuan Tung
Keyword(s):  
Free Surface ◽  
Free Boundary ◽  
Dispersion Equation ◽  
Half Space ◽  
Rayleigh Waves ◽  
Plane Waves ◽  
Transversely Isotropic ◽  
Frequency Parameter ◽  
Free Condition ◽  
Stress Free Boundary

This study is devoted to investigate the propagation of Rayleigh-type waves in transversely isotropic nonlocal piezoelastic half-space.  When the stress-free boundary is maintained at charge-free condition, the dispersion equation for the propagation of Rayleigh waves at the free surface of transversely isotropic piezoelastic solids has been obtained. Based on the obtained dispersion equation, the effect of the nonlocality on the speed of Rayleigh wave is numerically considered. The dependence of velocities of plane waves in transversely isotropic nonlocal piezoelastic medium on the direction of propagation as well as non-dimensional frequency parameter has been also illustrated.

Acoustic wave propagation in tilted transversely isotropic media: Incorporating topography

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. C265-C278 ◽  
Author(s):  
Jeffrey Shragge
Keyword(s):  
Wave Propagation ◽  
Free Surface ◽  
Surface Topography ◽  
Domain Boundary ◽  
Waveform Inversion ◽  
Transversely Isotropic ◽  
Surface Boundary ◽  
Reverse Time ◽  
Time Migration ◽  
Tti Media

Simulating two-way acoustic wavefield propagation directly from a free-surface boundary in the presence of topography remains a computational challenge for applications of reverse time migration (RTM) or full-waveform inversion (FWI). For land-seismic settings involving heavily reworked geology (e.g., fold and thrust belts), two-way wavefield propagation operators should also handle commonly observed complex anisotropy including tilted transversely isotropic (TTI) media. To address these issues, I have extended a system of coupled partial differential equations used to model 3D acoustic TTI wave propagation in Cartesian coordinates to more generalized 3D geometries, including a deformed computational mesh with a domain boundary conformal to free-surface topography. A generalized curvilinear transformation is used to specify a system of equations governing 3D acoustic TTI wave propagation in the “topographic” coordinate system. The developed finite-difference time-domain numerical solution adapts existing Cartesian TTI operators to this more generalized geometry with little additional computational overhead. Numerical evaluations illustrate that 2D and 3D impulse responses are well-matched to those simulated on Cartesian meshes and analytic traveltimes for homogeneous elliptical TTI media. Accordingly, these generalized acoustic TTI propagators and their numerical adjoints are useful for undertaking most RTM or FWI applications using computational domains conforming to free-surface topography.

scholarly journals Propagation of Plane Waves in a Thermally Conducting Mixture

2011 ◽  
Vol 2011 ◽  
pp. 1-12
Author(s):  
Baljeet Singh
Keyword(s):  
Free Surface ◽  
Longitudinal Wave ◽  
Plane Waves ◽  
Generalized Thermoelasticity ◽  
Elastic Solid ◽  
Reflection Coefficients ◽  
Governing Equations ◽  
Transverse Waves ◽  
Longitudinal Waves ◽  
Thermally Conducting

The governing equations for generalized thermoelasticity of a mixture of an elastic solid and a Newtonian fluid are formulated in the context of Lord-Shulman and Green-Lindsay theories of generalized thermoelasticity. These equations are solved to show the existence of three coupled longitudinal waves and two coupled transverse waves, which are dispersive in nature. Reflection from a thermally insulated stress-free surface is considered for incidence of coupled longitudinal wave. The speeds and reflection coefficients of plane waves are computed numerically for a particular model.

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