*HEADING
 1D transient wave propagation in an acoustic medium with CLOAD on dof 8. AC2D4
 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=NO
*NODE
    1, 0,
  101, 1,
 1001, 0, 1
 1101, 1, 1
*NGEN,NSET=CHANNEL
    1,101
 1001,1101
*NSET,NSET=SAMPLE,GENERATE
 1,101
*NSET,NSET=LOAD
 1,1001
*ELEMENT,TYPE=AC2D4
 1,1,2,1002,1001
*ELGEN,ELSET=CHANNEL
 1,100
*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
**
*STEP,INC=1000
*DYNAMIC
.0001,.0044
** Define nonreflective boundary at x=1
*IMPEDANCE
 100,I2
**
** Prescribe volume acceleration inwards
**     of  a0 * cross-section= 3., therefore a0=1.
**     Distribute half to each node on edge.
*CLOAD
 LOAD,8,1.5
**
*EL PRINT,FREQ=0
*NODE PRINT,NSET=SAMPLE,FREQ=22
 POR,
*OUTPUT,VAR=PRESELECT,FIELD,FREQ=1
*OUTPUT,VAR=PRESELECT,HISTORY,FREQ=1
*ENDSTEP