Print Email Facebook Twitter Numerical noise suppression for wave propagation with finite elements in first-order form by an extended source term Title Numerical noise suppression for wave propagation with finite elements in first-order form by an extended source term Author Shamasundar, R. (TU Delft Applied Geophysics and Petrophysics) Mulder, W.A. (TU Delft Applied Geophysics and Petrophysics; Shell Global Solutions International B.V.) Date 2018 Abstract Finite elements can, in some cases, outperform finite-difference methods for modelling wave propagation in complex geological models with topography. In the weak form of the finiteelement method, the delta function is a natural way to represent a point source. If, instead of the usual second-order form, the first-order form of the wave equation is considered, this is no longer true. Fourier analysis for a simple case shows that the spatial operator corresponding tothe first-order form has short-wavelength null-vectors. Once excited, these modes are not seen by the spatial operator but only by the time- stepping scheme and show up as noise. A sourcewith a larger spatial extent, for instance a Gaussian or a tapered sinc, can avoid the excitation of problematic short wavelengths. A series of numerical experiments on a 2-D problem with an exact solution provides a suggestion for the best choice of parameters for these sourceterm distributions. The tapered sinc provided the best results and the resulting accuracy can be better than that of the second-order form. The higher operation count of the former, however, does not make it more efficient in terms of accuracy for a given computational effort, at least not for the 2-D examples considered here To reference this document use: http://resolver.tudelft.nl/uuid:f5ce58cd-e20d-4ec4-88b1-a43abc43511a DOI https://doi.org/10.1093/gji/ggy337 ISSN 0956-540X Source Geophysical Journal International, 215 (2), 1231–1240 Part of collection Institutional Repository Document type journal article Rights © 2018 R. Shamasundar, W.A. Mulder Files PDF ggy337.pdf 1.77 MB Close viewer /islandora/object/uuid:f5ce58cd-e20d-4ec4-88b1-a43abc43511a/datastream/OBJ/view