*HEADING
 1D transient wave propagation, acoustic medium, incident wave load, planar
 and defined through acceleration amplitude
**
** C = root (K/rho)= 343.05 m/s   K=bulk mod, rho=density.  
**
** Analytical solution to prescribed constant acceleration of a0 at x=0
** 
** p(x,t) = (K a0 / c^2) (ct - x)  for x < ct
**        = 0  			   for x > ct
** 
*PREPRINT,ECHO=NO,HISTORY=NO,MODEL=YES
*NODE, NSET=ODB_NSET
    1, 0,
  101, 1,
  501, 0,.5E-2
  601, 1,.5E-2
 1001, 0, 1.E-2
 1101, 1, 1.E-2
 1501, 0, 1.E-2, -1.E-2
 1601, 1, 1.E-2, -1.E-2
 2001, 0, 1.E-2, -0.5E-2
 2101, 1, 1.E-2, -0.5E-2
 2501, 0, 0, -1.E-2
 2601, 1, 0, -1.E-2
 3001, 0,.5E-2, -1.E-2
 3101, 1,.5E-2, -1.E-2
 3501, 0, 0, -0.5E-2
 3601, 1, 0, -0.5E-2
*NGEN,NSET=CHANNEL
    1,101
  501,601
 1001,1101
 1501,1601
 2001,2101
 2501,2601
 3001,3101
 3501,3601
*NSET,NSET=SAMPLE,GENERATE
 1,101
*ELEMENT,TYPE=AC3D20
 1,1,3,2503,2501,1001,1003,1503,1501,
 2,3503,2502,3501,1002,2003,1502,2001,
 501,503,3003,3001
*ELGEN,ELSET=CHANNEL
 1,50,2
**************************
*SURFACE,NAME=IW_LOAD
 1,S6
**************************
*SOLID SECTION,MATERIAL=AIR,ELSET=CHANNEL
**
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
**
**************************
*INCIDENT WAVE PROPERTY,NAME=IWPROP,TYPE=PLANE
0.0,0.0,
-10.0,0.0,
*INCIDENT WAVE FLUID PROPERTY
0.1424E6,1.21,0.0
*AMPLITUDE,DEFINITION=TABULAR,NAME=ACCVTIME
0.0,-1.0,1.0,-1.0
**************************
*RESTART,WRITE
**
*STEP,INC=1000
*DYNAMIC
.0001,.0044
** DEFINE NONREFLECTIVE BOUNDARY AT X=1
*IMPEDANCE
 50,I4
**
*INCIDENT WAVE,ACCELERATIONAMPLITUDE=ACCVTIME,PROPERTY=IWPROP
IW_LOAD,1
**
*EL PRINT,FREQ=0
*NODE PRINT,NSET=SAMPLE,FREQ=22
 POR,
*OUTPUT,FIELD,FREQUENCY=1
*NODE OUTPUT
 POR,
*OUTPUT,HISTORY,FREQUENCY=1
*NODE OUTPUT,NSET=SAMPLE
 POR,
*ENDSTEP