Scattering of elastic waves in media with a random distribution of fluid-filled cavities: theory and numerical modelling
نویسندگان
چکیده
S U M M A R Y The propagation of elastic waves is modelled in media with a random distribution of fluidfilled circular cavities, which display high physical impedance in contrast to background media. Theoretical attenuation expressions for media with circular cavities, which may be filled with any material (e.g. vacuum, fluid, elastic materials), are formulated using an ensemble treatment for first-order transmitted waves. Numerical estimates of scattering attenuation rates agree with the theoretical results well. The scattering attenuations (Q−1) are proportional to the scale of cavities and the number density (η, number of cavities per area in a medium). The decrease of primary energy with the size of cavities does not result in the increase of coda energy owing to the increase of both purely backscattered waves from cavities and the trapped waves inside cavities. Scattering properties (e.g. scattering attenuation, coda energy, phase fluctuation of primary waves) in media with randomly distributed cavities are very different from those in stochastic random media. It appears that heterogeneities with high impedance in the earth may not be well represented with stochastic random heterogeneities.
منابع مشابه
Scattering Attenuation of 2D Elastic Waves: Theory and Numerical Modeling Using a Wavelet-Based Method
The passage of seismic waves through highly heterogeneous media leads to significant scattering of seismic energy and an apparent attenuation of seismic signals emerging from the heterogeneous zone. The size of this scattering attenuation depends on the correlation properties of the medium, the rates of Pand S-wave velocities, and frequency content of the incident waves. An estimate of the effe...
متن کاملRandom Matrix Theory of Scattering in Chaotic and Disordered Media
We review the randommatrix theory describing elastic scattering through zero-dimensional ballistic cavities (having chaotic classical dynamics) and quasi-one dimensional disordered systems. In zero dimension, general symmetry considerations (flux conservation and time reversal symmetry) are only considered, while the combination law of scatterers put in series is taken into account in quasi-one...
متن کاملPropagation of Waves at an Interface of Heat Conducting Elastic Solid and Micropolar Fluid Media
The present investigation is concerned with the reflection and transmission coefficients of plane waves at the interface of generalized thermoelastic solid half space and heat conducting micropolar fluid half- space. The amplitude ratios of various reflected and transmitted waves with various angle of incidence have been computed numerically and depicted graphically. Micropolarity and thermal r...
متن کاملA Generalized Thermo-Elastic Diffusion Problem in a Functionally Graded Rotating Media Using Fractional Order Theory
A generalized thermo-elastic diffusion problem in a functionally graded isotropic, unbounded, rotating elastic medium due to a periodically varying heat source in the context of fractional order theory is considered in our present work. The governing equations of the theory for a functionally graded material with GNIII model are established. Analytical solution of the problem is derived in Lapl...
متن کاملFinite - element modelling of elastic wave propagation and scattering within heterogeneous media
The scattering treated here arises when elastic waves propagate within a heterogeneous medium defined by random spatial fluctuation of its elastic properties. Whereas classical analytical studies are based on lower-order scattering assumptions, numerical methods conversely present no such limitations by inherently incorporating multiple scattering. Until now, studies have typically been limited...
متن کامل