Frequency-Domain Finite-Difference Acoustic Modeling with Free Surface Topography using Embedded Boundary Method
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paper11_Li_topography_2010.pdf
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Author(s)
Li, Junlun
Zhang, Yang
Toksoz, M. Nafi
Date Issued
2010
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;2010-11
Abstract
In this paper, we present a method to model acoustic wave propagation in the frequencydomain
in the presence of free surface topography using the embedded boundary method. The
advantage of this method is to solve for the pressure field at each frequency on regular finite
difference grids but with sub-cell resolution (up to 2nd order accuracy) for the irregular free
surface. The topographic free surface condition is implemented in 2nd order accuracy, as in the
regular domain so that global 2nd order accuracy is guaranteed. We use the level set method to
obtain the projection points and normal directions corresponding to the ghost points in the
scheme in the irregular domain. The computational cost for solving the modified sparse matrix
for the pressure field increases very little compared to that for a flat surface. We have
benchmarked our solver with a 2-D Gaussian hill model and simulated wave propagating in a
modified Canadian foothills model. This solver can be used as the forward engine in the full
waveform inversion, and we are working underway to perform full waveform inversions with
real land survey data with considerable presence of surface topography.
Subjects
Modeling
Numerical methods
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