Acoustic Staggered Grid Modeling in IWAVE |
frame13 Figure 1. Point source field, homogeneous medium with km/s, at 1.2 s |
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frame40-1 Figure 2. Point source field at 4.0 s, after interaction with reflecting (zero-pressure) boundaries |
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frame40-2 Figure 3. Point source field at 4.0 s, after interaction with 250 m PML boundary zones on bottom and sides () - same grey scale as Figure 2. Longest wavelength carrying significant energy is roughly 500 m. |
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frame40-3 Figure 4. Point source field at 4.0 s, after interaction with 100 m PML boundary zones on bottom and sides () - same grey scale as Figure 2. |
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bm1 Figure 5. Dome bulk modulus |
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by1 Figure 6. Dome buoyancy |
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data1 Figure 7. 2D shot record, (2,4) staggered grid scheme, 5 m, appropriate , 301 traces: shot x = 3300 m, shot z = 40 m, receiver x = 100 - 6100 m, receiver z = 20 m, number of time samples = 1501, time sample interval = 2 ms. Source pulse = zero phase trapezoidal [0.0, 2.4, 15.0, 20.0] Hz bandpass filter. |
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trace Figure 8. Trace 100 (receiver x = 2100 m) for 20 m (black), 10 m (blue), 5 m (green), and 2.5 m (red). Note arrival time discrepancy after 1 s: this is the interface error discussed in (Symes and Vdovina, 2009). Except for the 20 m result, grid dispersion error is minimal. |
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wtrace Figure 9. Trace 100 detail, 1.8-2.5 s, showing more clearly the first-order interface error: the time shift between computed events and the truth (the 2.5 m result, more or less) is proportional to , or equivalently to . |
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data8k1 Figure 10. 2D shot record, (2,8) scheme, other parameters as in Figure 7. |
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trace8k Figure 11. Trace 100 computed with the (2,8) scheme, other parameters as described in the captions of Figures 7 and 8. |
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wtrace8k Figure 12. Trace 100 detail, 1.8-2.5 s, (2,8) scheme.. Comparing to Figure 9, notice that the dispersion error for the 20 m grid is considerably smaller, but the results for finer grids are nearly identical to those produced by the (2,4) grids - almost all of the remaining error is due to the presence of discontinuities in the model. |
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Acoustic Staggered Grid Modeling in IWAVE |