*HEADING
 1D transient wave propagation in an acoustic medium with CLOAD on dof 8. AC3D8
 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, Nset=ODB_NSET
    1, 0,
  101, 1,
 1001, 0, 1e-2
 1101, 1, 1e-2
 1501, 0, 1e-2, -1e-2
 1601, 1, 1e-2, -1e-2
 2501, 0, 0, -1e-2
 2601, 1, 0, -1e-2
*NGEN,NSET=CHANNEL_NODES
    1,101
 1001,1101
 1501,1601
 2501,2601
*NSET,NSET=SAMPLE_NODES,GENERATE
 1,101
*NSET,NSET=LOADED_NODES
 1,1001,1501,2501
*ELEMENT,TYPE=AC3D8
 1,1,2,2502,2501,1001,1002,1502,1501
*ELGEN,ELSET=CHANNEL
 1,100
*SOLID SECTION,MATERIAL=AIR,ELSET=CHANNEL
** Cross-section is 3.0  
**
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
**
** Define nonreflective boundary at x=1
** Using user calculated constants:
** 1/k1=0, 1/c1=1/(rho*c)
*IMPEDANCE PROPERTY,NAME=NONREF
 0, 2.41E-3
**
*RESTART,WRITE
**
**
** Sets added by addodb
**
*Elset,Elset=ODB_ESET
CHANNEL,
**
**
*Nset, Nset=ODB_NSET
ODB_NSET, CHANNEL_NODES, SAMPLE_NODES, LOADED_NODES
**
**
*STEP,INC=1000
*DYNAMIC,DIRECT
.0001,.0044
*IMPEDANCE,prop=nonref
 100,I4,
**
** Prescribe unit particle acceleration a0 inwards,
** so that _volume_ acceleration is a0 * cross-section.
**  Distribute 1/4 to each corner node:   
*CLOAD
 LOADED_NODES,8,.25e-4
**
*EL PRINT,FREQ=0
*NODE PRINT,NSET=SAMPLE_NODES,FREQ=22
 POR,
*OUTPUT,FIELD,VARIABLE=PRESELECT,FREQ=1
*OUTPUT,FIELD,Frequency=22
*NODE OUTPUT,NSET=SAMPLE_NODES
 POR,
*OUTPUT,HISTORY,Frequency=22
*NODE OUTPUT,NSET=SAMPLE_NODES
 POR,
*ENDSTEP