*HEADING
 ECA3AFAT: ACAX3 AND CAX4 ELEMENTS
 Tube with nonreflective end condtion and *TIE constraint.
 Part of the air in the tube is modelled with continuum elements
 with air properties.
********************
*NODE, Nset=ODB_NSET
1,1000.0,0.0
21,1000.5,0.0
101,1000.0,0.025
121,1000.5,0.025
*NGEN,NSET=NALL
1,21
101,121
*NCOPY,OLDSET=NALL,NEWSET=NSOL,CHANGENUMBER=10000,SHIFT
0.0,0.0,0.0
1.0,0.0,0.0,0.0,1.0,0.0
*NSET,NSET=SAMPLE,GENERATE
1,41
*NSET,NSET=LOAD
1,101
** First 10 elements are acoustic
*ELEMENT,TYPE=ACAX3
1,1,2,102
2,102,101,1
*ELGEN,ELSET=ACOU
1,5,1,2
2,5,1,2
** Then 5 continuum elements
*ELEMENT,TYPE=CAX4
1006,10006,10007,10107,10106
*ELGEN,ELSET=STRUCT
1006,5,1,1
** Next 20 elements are acoustic
*ELEMENT,TYPE=ACAX3
31,11,12,112
32,112,111,11
*ELGEN,ELSET=ACOU
31,10,1,2
32,10,1,2
*ELSET,ELSET=NONREF
49,
************************************************
*SURFACE,TYPE=ELEMENT,NAME=ACR
9,S2
*SURFACE,TYPE=ELEMENT,NAME=SOL
1006,S4
*SURFACE,TYPE=ELEMENT,NAME=SOR
1010,S2
*SURFACE,TYPE=ELEMENT,NAME=ACL
32,S2
*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, NALL, SAMPLE, LOAD
************************************************  
*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
 NONREF,I2
**
** Conditions at x=0 : Define the source inward accel
** to be  a =  omega i, so v (inward) = 1.
**
*CLOAD,LOAD CASE=2, AMP=OMEGA
LOAD, 8, 78.539816
** simulation of uniaxial condition
*BOUNDARY
NSOL,2,2
*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