Progress on Forward Modeling for Acoustic-Propagation Simulations

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

Joe Werne(1)

Keith Julien(2)

(1)NorthWest Research Associates, Inc. (NWRA) Colorado Research Associates Division (CoRA) 3380 Mitchell Lane, Boulder, CO 80301 werne@cora.nwra.com

(2)Department of Applied Mathematics University of Colorado, Boulder, CO julien@colorado.edu

Julien, Werne CU, CoRA/NWRA

February 2004

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

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

Test Cases:

Acoustic wave-packet propagation, inviscid evolution

1) 1-D with constant sound speed (test diffusion/dispersion)

2) 3-D density anomaly (coin in two orientations)

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

1) 1-D with constant sound speed (test numerical diffusion/dispersion):

gridpoint

gridpoint

0 t 140 t 280 t After 2400 t, amplitude drops by 0.7%.

Negligible dispersion and diffusion errors.

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

2) 3-D density anomaly (coin in two orientations):

12.5 Mm

50 Mm C0=36 km/s

C1=50 km/s

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

2) 3-D density anomaly (coin in two orientations):

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

2) 3-D density anomaly (coin in two orientations):

22 Mm

4Mm 5 mHz

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

2) 3-D density anomaly (coin in two orientations):

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

2) 3-D density anomaly (coin in two orientations):

February 2004 Julien, Werne CU, CoRA/NWRA

Julien, Werne CU, CoRA/NWRA

February 2004

Progress on Forward Modeling for Acoustic-Propagation Simulations

Continued Test Work:

Sound-speed perturbations

Subsurface flows

Subsurface magnetic fields