*HEADING
 EC3AAFAS: AC3D10 and ASI elements
 1D transient wave propagation in an acoustic medium
 prescribed acceleration on dof. 1.
 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
*NGEN,NSET=CHANNEL
*NSET,NSET=SAMPLE,GENERATE
*NSET,NSET=CRNRLOAD
*NSET,NSET=EDGELOAD
*NSET,NSET=LOADED
*ELEMENT,TYPE=AC3D10
*ELGEN,ELSET=CHANNEL
**
** degenerated ASI4 elements used - ASI3 is a line element.
**
*ELEMENT,TYPE=ASI4,ELSET=LOAD
*INTERFACE, ELSET=LOAD
*SOLID SECTION,MATERIAL=AIR,ELSET=CHANNEL
*surface, NAME=NRS
 300,S3
 297,S3
** Cross-section is 3.0
**
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
*RESTART,WRITE
*Elset,Elset=ODB_ESET
CHANNEL,
*Nset, Nset=ODB_NSET
ODB_NSET, CHANNEL, SAMPLE, CRNRLOAD
EDGELOAD, LOADED
**
**
*STEP,INC=1000
*DYNAMIC
.0001,.0036
** Define nonreflective boundary at x=1
*IMPEDANCE
 300,I3
 297,I3
**
**  Prescribe unit _particle_ acceleration a0 inwards;
**
*BOUNDARY,TYPE=ACCELERATION
 LOADED,1,1,1.00
**
*EL PRINT,FREQ=0
*NODE PRINT,NSET=SAMPLE,FREQ=6
 POR,
*NODE FILE,NSET=SAMPLE,FREQ=6
 POR,
*OUTPUT,FIELD,VARIABLE=PRESELECT,OP=ADD,FREQUENCY=9999
*OUTPUT,FIELD, OP=ADD,Frequency=6
*NODE OUTPUT,NSET=SAMPLE
 POR,
*OUTPUT,HISTORY,OP=ADD,Frequency=6
*NODE OUTPUT,NSET=SAMPLE
 POR,
*ENDSTEP
**
*STEP,INC=1000
*DYNAMIC
.0001,.0008
*IMPEDANCE,OP=NEW
*SIMPEDANCE
 NRS,
*BOUNDARY,TYPE=ACCELERATION
 LOADED,1,1,1.00
*EL PRINT,FREQ=0
*NODE PRINT,NSET=SAMPLE,FREQ=6
 POR,
*NODE FILE,NSET=SAMPLE,FREQ=6
 POR,
*OUTPUT,FIELD,VARIABLE=PRESELECT,OP=ADD,FREQUENCY=9999
*OUTPUT,FIELD, OP=ADD,Frequency=6
*NODE OUTPUT,NSET=SAMPLE
 POR,
*OUTPUT,HISTORY,OP=ADD,Frequency=6
*NODE OUTPUT,NSET=SAMPLE
 POR,
*ENDSTEP