*HEADING
 EC348AFAT: AC3D4 AND C3D8 ELEMENTS
 Tube with nonreflective end-condition and *TIE constraint.
 Part of the air in the tube is modelled with continuum elements
 with air properties.
************************************************
*preprint,model=yes,history=yes
*NODE, Nset=ODB_NSET
1, 
41,.5
101,,0.0125
141,0.5,0.0125
201,,0.025
241,0.5,0.025
*NGEN,NSET=NBACK
1,41
101,141
201,241
*NCOPY,CHANGE NUMBER=600, OLD SET=NBACK, NEW SET=NFRONT,SHIFT
0.0,0.0,0.025

*NSET,NSET=NALL
NBACK,NFRONT
*NSET,NSET=SAMPLE,GEN
1,41
*NSET,NSET=LOAD1
1,201,801,601
************************************************
*NCOPY,OLDSET=NALL,NEWSET=NSOL,CHANGENUMBER=1000,SHIFT
0.0,0.0,0.0
1.0,0.0,0.0,0.0,1.0,0.0
************************************************
** First 30 elements are acoustic
*ELEMENT,TYPE=AC3D4
 1,    1,  601,  603,  201
 2,  601,  603,  201,  801
 3,  603,  201,  801,  803
 4,  603,    3,    1,  803
 5,    3,    1,  803,  203
 6,    1,  803,  203,  201
*ELGEN,ELSET=ACOU
1,5,2,6
2,5,2,6
3,5,2,6
4,5,2,6
5,5,2,6
6,5,2,6
** Then 5 continuum elements
*ELEMENT,TYPE=C3D8
1006,1011,1611,1613,1013,  1211,1811,1813,1213,
*ELGEN,ELSET=STRUCT
1006,5,2,1
** Next elements are acoustic
*ELEMENT,TYPE=AC3D4
101,   21,  621,  623,  221
102,  621,  623,  221,  821
103,  623,  221,  821,  823
104,  623,   23,   21,  823
105,   23,   21,  823,  223
106,   21,  823,  223,  221
*ELGEN,ELSET=ACOU
101,10,2,6
102,10,2,6
103,10,2,6
104,10,2,6
105,10,2,6
106,10,2,6
*ELSET,ELSET=NONREF
120,
************************************************
*SURFACE,TYPE=ELEMENT,NAME=ACR
28,S2
29,S4
*SURFACE,TYPE=ELEMENT,NAME=SOL
1006,S3
*SURFACE,TYPE=ELEMENT,NAME=SOR
1010,S5
*SURFACE,TYPE=ELEMENT,NAME=ACL
101,S2
102,S4
*TIE,NAME=CRAVAT
SOL,ACR
ACL,SOR
************************************************
**
**  Acoustic Element Properties
**
*SOLID SECTION,MATERIAL=AIR,ELSET=ACOU
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
************************************************
**
**  Continuum Element Properties
**
*SOLID SECTION,MATERIAL=AIRSOLID,ELSET=STRUCT
*MATERIAL,NAME=AIRSOLID
*DENSITY
 1.21,
*ELASTIC
 0.1424E6,
************************************************
*AMPLITUDE,NAME=OMEGA
0.,0., 1E6,6.2831853E6
************************************************
**       ** ANALYTIC SOLUTION  **
**  
**  at freq=100,
**  Impedance: Z = root( K_f rho )
**               = 415.095
**  Propagation constant 
**             b = i (omega/K_f) Z
**               = 1.8315  i
**
**  Solution: with nonreflective end,
**  Complex pressure
**             p(x) = Z v(0) exp( - b x)
**  i.e. |p(x)| = |Z v(0)| exp ( - Re(b) x)
**              =  415.095
**
**       Arg(p) = Arg(Z) - Im(b) x
**       ppor   = - 104.94 x
**
************************************************  
*Elset,Elset=ODB_ESET
ACOU, STRUCT
*Nset, Nset=ODB_NSET
ODB_NSET, NBACK, NFRONT
NALL, SAMPLE, LOAD1
************************************************  
*STEP
*STEADY STATE DYNAMIC,DIRECT
100,
**  For reference, these IMPEDANCE PROPERTY
**  constants could be used to specify the nonreflecting 
**  condition at the given frequency:
**  1/k1= 0, 1/c1= 2.40908E-03
**        0,       1/Z
**
*IMPEDANCE
158,I2
159,I4
**
** Conditions at x=0 : Define the source inward accel
** to be  a =  omega i, so v (inward) = 1.
** *AMPLITUDE card enforces (2*pi)*f factor. 
** *CLOAD needs only to carry total area, distributed
** to nodes.
**
*CLOAD,LOAD CASE=2, AMP=OMEGA
LOAD1, 8, 1.5625E-04
** simulation of uniaxial condition
*BOUNDARY
NSOL,2,3
*NODE PRINT, NSET=SAMPLE
COORD,POR,PPOR
*OUTPUT,FIELD,OP=ADD,FREQUENCY=9999
*ELEMENT OUTPUT,ELSET=STRUCT
S
*NODE OUTPUT,NSET=SAMPLE
POR,
*OUTPUT,HISTORY,OP=ADD,FREQUENCY=9999
*NODE OUTPUT,NSET=SAMPLE
POR,
*ELEMENT OUTPUT,ELSET=STRUCT
COORD,S11
*END STEP