*HEADING
 1D transient wave propagation in an acoustic medium with CLOAD on dof 8. AC1D3
 Verification problem: Transient Dynamics Tests
**
** C = root (K/rho)= 343.05 m/s   K=bulk mod, rho=density.  
**
** Analytic 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
*NGEN, Nset=ODB_NSET
   1,101
*NSET,NSET=CHANNEL,GENERATE
 1,101
*ELEMENT,TYPE=AC1D3
 1,1,2,3
*ELGEN,ELSET=CHANNEL
 1,50,2
*SOLID SECTION,MATERIAL=AIR,ELSET=CHANNEL
 3., 
** Cross-section is 3.0  
**
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
**
**
*RESTART,WRITE
**
**
** Sets added by addodb
**
*Elset,Elset=ODB_ESET
CHANNEL,
**
**
*Nset, Nset=ODB_NSET
ODB_NSET, CHANNEL
**
**
*STEP,INC=1000
*DYNAMIC
.0001,.0044
** Define nonreflective boundary at x=1
*IMPEDANCE
 50,I2
**
** Prescribe volume acceleration inwards
**   of  a0 * cross-section= 3., therefore a0=1
*CLOAD
 1,8,3.
*EL PRINT,FREQ=0
*NODE PRINT,NSET=CHANNEL,FREQ=22
 POR,
*OUTPUT,FIELD,Frequency=1
*NODE OUTPUT
 POR,
*OUTPUT,FIELD,Frequency=22
*NODE OUTPUT,NSET=CHANNEL
 POR,
*OUTPUT,HISTORY,Frequency=22
*NODE OUTPUT,NSET=CHANNEL
 POR,
*ENDSTEP