Progress on Forward Modeling for AcousticPropagation Simulations

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Progress on Forward Modeling for
Acoustic-Propagation Simulations
Joe Werne(1) Keith Julien(2) (1)Nort
hWest Research Associates, Inc. (NWRA)
Colorado Research Associates Division (CoRA)
3380 Mitchell Lane, Boulder, CO 80301
werne_at_cora.nwra.com (2)Department of Applied
Mathematics University of Colorado,
Boulder, CO julien_at_colorado.edu
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Progress on Forward Modeling for
Acoustic-Propagation Simulations

• Code Development
• Cartesian Geometry
• Linear Acoustic Modes
• 3D MHD
• Spectral Accuracy in all 3 Directions
• 3rd-order Runge-Kutta time stepping w/internal
  Newton-Raphson iteration scheme for implicit
  operations
• Currently generalizing and adapting
  wave-radiation formalism for acoustic-wave
  radiation

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Progress on Forward Modeling for
Acoustic-Propagation Simulations

• Test Cases
• Acoustic wave-packet propagation, inviscid
  evolution
• 1-D with constant sound speed (test
  diffusion/dispersion)
• 3-D density anomaly (coin in two orientations)

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Progress on Forward Modeling for
Acoustic-Propagation Simulations
1) 1-D with constant sound speed (test
numerical diffusion/dispersion)
0 dt
140 dt
280 dt
After 2400 dt, amplitude drops by ?
0.7. Negligible dispersion and diffusion errors.
gridpoint
gridpoint
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Progress on Forward Modeling for
Acoustic-Propagation Simulations
2) 3-D density anomaly (coin in two
orientations)
C036 km/s
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Progress on Forward Modeling for
Acoustic-Propagation Simulations
2) 3-D density anomaly (coin in two
orientations)
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Progress on Forward Modeling for
Acoustic-Propagation Simulations
2) 3-D density anomaly (coin in two
orientations)
8
Progress on Forward Modeling for
Acoustic-Propagation Simulations
2) 3-D density anomaly (coin in two
orientations)
9
Progress on Forward Modeling for
Acoustic-Propagation Simulations
2) 3-D density anomaly (coin in two
orientations)
February 2004
Julien, Werne
CU, CoRA/NWRA
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Progress on Forward Modeling for
Acoustic-Propagation Simulations

• Continued Test Work
• Sound-speed perturbations
• Subsurface flows
• Subsurface magnetic fields