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Felipe A. G. Silva

Publications and source records attributed to Felipe A. G. Silva.

2 recordsLinked to original sources

Arbitrary high order shaped stencils for time domain finite difference schemes in seismic wave propagation

Finite Difference Schemes are widely used in the approximation of different hyperbolic (wave-like) differential equations, and are particularly important for seismic wave modelling and its applications. Classical methods based on Taylor Series are dominant in the literature; however, it is known that these methods can suffer from excessive numerical dispersion. In this paper, we review and extend existing high-order in space finite difference schemes for acoustic wave propagation, featuring different stencil geometries ranging from classical cross stencils to stencils with rhombus or square-like shapes, and propose a general mathematical framework for their derivation. The numerical implementation is performed in a symbolic, high-level framework (Devito), which compiles and runs highly optimized, stencil-based computations, allowing for a low-level interpretation of the methods efficiency. We demonstrate that non-cross stencil shapes, such as rhombus and square-based stencils, do not necessarily provide added accuracy or dispersion reduction in general, despite their increased computational cost. However, results on both idealized and realistic velocity models confirm the benefits of using dispersion-optimized cross-stencils, indicating adequate accuracy with reduced computational cost on more compact stencils compared to classic approaches. Finally, our implementation of the methods provides ease of use for full-scale acoustic seismic inversion problems using Devito.

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On Godunov-type finite volume methods for seismic wave propagation

The computational complexity of simulating seismic waves demands continual exploration of more efficient numerical methods. While Finite Volume methods are widely acclaimed for tackling general nonlinear hyperbolic (wave) problems, their application in realistic seismic wave simulation remains uncommon, with rare investigations in the literature. Furthermore, seismic wavefields are influenced by sharp subsurface interfaces frequently encountered in realistic models, which could, in principle, be adequately solved with Finite Volume methods. In this study, we delved into two Finite Volume (FV) methods to assess their efficacy and competitiveness in seismic wave simulations, compared to traditional Finite Difference schemes. We investigated Gudunov-type FV methods: an upwind method called wave propagation algorithm (WPA), and a Central-Upwind type method (CUp). Our numerical analysis uncovered that these finite volume methods could provide less dispersion (albeit increased dissipation) compared to finite differences for seismic problems characterized by velocity profiles with abrupt transitions in the velocity. However, when applied to more realistic seismic models, finite volume methods yielded unfavorable outcomes compared to finite difference methods, the latter offering lower computational costs and higher accuracy. This highlights that despite the potential advantages of finite volume methods, such as their conservative nature and aptitude for accurately capturing shock waves in specific contexts, our results indicate that they are only advantageous for seismic simulations when unrealistic abrupt transitions are present in the velocity models in the velocity models.

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