SUFDMOD2 - Finite-Difference MODeling (2nd
order) for acoustic wave equation
sufdmod2 <vfile
>wfile nx= nz= tmax= xs= zs= [optional parameters]
Required
Parameters:
<vfile file
containing velocity[nx][nz]
>wfile file
containing waves[nx][nz] for time steps
nx= number
of x samples (2nd dimension)
nz= number
of z samples (1st dimension)
xs= x
coordinates of source
zs= z
coordinates of source
tmax= maximum
time
Optional Parameters:
nt=1+tmax/dt number
of time samples (dt determined for stability)
mt=1 number of
time steps (dt) per output time step
dx=1.0 x
sampling interval
fx=0.0 first
x sample
dz=1.0 z
sampling interval
fz=0.0 first
z sample
fmax = vmin/(10.0*h) maximum frequency in source wavelet
fpeak=0.5*fmax peak frequency in ricker wavelet
dfile= input file
containing density[nx][nz]
vsx= x
coordinate of vertical line of seismograms
hsz= z
coordinate of horizontal line of seismograms
vsfile= output
file for vertical line of seismograms[nz][nt]
hsfile= output file
for horizontal line of seismograms[nx][nt]
ssfile= output file
for source point seismograms[nt]
verbose=0 =1
for diagnostic messages, =2 for more
abs=1,1,1,1 Absorbing
boundary conditions on top,left,bottom,right
sides of the
model.
=0,1,1,1
for free surface condition on the top
...PML parameters....
pml_max=1000.0 PML absorption parameter
pml_thick=0 half-thickness of pml layer (0 = do not use PML)
Notes:
This program uses the traditional explicit
second order differencing
method.
Two different absorbing boundary condition
schemes are available. The
first
is a traditional absorbing boundary condition scheme created by
Hale, 1990. The second is based on the
perfectly matched layer (PML)
method of Berenger, 1995.
Authors:
CWP:Dave Hale
CWP:modified for SU by John Stockwell, 1993.
CWP:added frequency specification
of wavelet: Craig Artley, 1993
TAMU:added PML absorbing boundary condition:
Michael Holzrichter,
1998
References: (Hale's absobing
boundary conditions)
Clayton, R.
W., and Engquist, B., 1977, Absorbing boundary conditions
for acoustic and elastic wave equations,
Bull. Seism. Soc. Am., 6,
1529-1540.
Clayton, R. W., and
Engquist, B., 1980, Absorbing boundary conditions
for wave equation migration, Geophysics, 45,
895-904.
Hale, D., 1990, Adaptive absorbing boundaries for
finite-difference
modeling of the
wave equation migration, unpublished report from the
Center for Wave Phenomena, Colorado School of
Mines.
Richtmyer, R. D., and
Morton, K. W., 1967, Difference methods for
initial-value problems, John Wiley & Sons, Inc, New
York.
Thomee, V., 1962, A
stable difference scheme for the mixed boundary problem
for a hyperbolic, first-order system in two
dimensions, J. Soc. Indust.
Appl.
Math., 10, 229-245.
Toldi,
J. L., and Hale, D., 1982, Data-dependent absorbing side boundaries,
Stanford Exploration Project Report SEP-30,
111-121.
References: (PML
boundary conditions)
Jean-Pierre
Berenger, ``A Perfectly Matched Layer for the Absorption of
Electromagnetic Waves,'' Journal of Computational Physics, vol.
114,
pp. 185-200.
Hastings, Schneider, and Broschat,
``Application of the perfectly
matched layer (PML) absorbing boundary condition to elastic
wave
propogation,'' Journal of the Accoustical Society of
America,
November, 1996.
Allen Taflove, ``Electromagnetic
Modeling: Finite Difference Time
Domain Methods'', Baltimore, Maryland: Johns
Hopkins University Press,
1995,
chap. 7, pp. 181-195.
Trace header fields set: ns, delrt, tracl, tracr, offset, d1,
d2,
sdepth, trid