A flat, compressed elastic film on a viscous layer is unstable. The film can form wrinkles to reduce the elastic energy. A linear perturbation analysis is performed to determine the critical wave number and the growth rate of the unstable modes. While the viscous layer has no effect on the critical wave number, its viscosity and thickness set the time scale for the growth of the perturbations. ...

and {ωk}k=1 ∈ C is a sequence of n distinct shifts. For example, shifted linear systems arise in model order reduction as well as in the geophysical exploration of both acoustic and elastic waves. In our application, we focus on wave propagation through elastic media in a frequency-domain formulation. This formulation has specific advantages when modeling visco-elastic effects. In order to impr...

If reciprocity principles are invoked in seismic data processing algorithms, one has to make sure that those processes maintain reciprocity. I outline briefly the derivation of reciprocity principles for elastic wave equations and show that discretized or approximated wave equations can lose symmetry properties and thus reciprocities. This effect is important if one is concernd about true-ampli...

Multiple-scattered waves usually are not useful for creating deterministic images of the interior of elastic media. However, in many applications, one is not so much interested in making a deterministic image as in detecting changes in the medium. Cases in point are volcano monitoring and measuring the change in hydrocarbon reservoirs during enhanced recovery operations. Coda wave interferometr...

Axisymmetric acoustic wave-modes propagating along buried water pipes have been investigated by the method of finite elements and experimentally. High precision dispersion relations are presented in this paper as a function of the geometry, the embedding material and the elastic modulus of the pipes. It is found that at low frequencies the fundamental axisymmetric acoustic mode of the water cyl...

An elastic wave propagating in a metal loses a portion of its energy from scattering caused by acoustic impedance differences existing at the boundaries of anisotropic grains. Theoretical scattering models capture this phenomena by assuming the incoming wave is described by an average elastic moduli tensorC0 i jkl (x) that is perturbed by a grain with elasticityCi jkl (x ′) where the scattering...

This article presents decoupling n-times absorbing boundary conditions designed to model acoustic and elastic wave propagation in a 2D transversely isotropic (TI) medium. More general n-times boundary conditions with absorbing parameters are also obtained by cascading first-order differential operators with parameters. These boundary conditions are approximated with simple finite-difference sch...