3D trapezoid-grid finite-difference time-domain (FDTD) method for seismic wave modeling
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Abstract:
To realize the reduction of calculation time and memory usage for seismic wave modeling on large scale model, we propose a 3D trapezoid-grid finite difference time domain (FDTD) method. It adopts the size-increasing trapezoid-grid mesh to fits the increasing trend in depth of seismic wave velocity, which can significantly reduce the oversampling in high-velocity region. The trapezoid transformation is used to alleviate the difficulty of processing irregular grids. We derive the 3D acoustic equation with the Convolutional Perfectly Matched Layer (CPML) absorbing boundary condition in the trapezoid coordinate system. Numerical tests are given to verify the effectiveness of our method. With comparable accuracy, our method can achieve about 54.1% improvement on efficiency and 88.7% reduction on memory compared with regular-grid FDTD method.Keywords:
Finite difference
Summary We present an alternative scheme for calculating finite difference coefficients in seismic wavefield modelling. This novel technique seeks to minimise the difference between the accurate value of spatial derivatives and the value calculated by the finite difference operator over all propagation angles. Since the coefficients vary adaptively with different velocities and source wavelet bandwidths, the method maximises the accuracy of the finite difference operator. Numerical examples demonstrate that this method is superior to standard finite difference methods whilst comparable to Zhang’s optimised finite difference method.
Finite difference
Finite difference scheme
Operator (biology)
Seismic migration
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