*HEADING
EXPLICIT ACOUSTIC 
*RESTART, WRITE
*PARAMETER
f=15
T1=0.005
omega=2*3.14159*f
*NODE, NSET=BACK_S
1, 0.0, 0.0, 0.0
7, 0.0, 1.0, 0.0
*NODE, NSET=FRONT_S
3, 2.0, 0.0, 0.0
9, 2.0, 1.0, 0.0
*NODE, NSET = CENTER_S
2, 1.0, 0.0, 0.0
8, 1.0, 1.0, 0.0
*NODE, NSET=BACK_F
 4, 2.0, 0.0, 0.0
10, 2.0, 1.0, 0.0
*NODE, NSET=FRONT_F
 6, 4.0, 0.0, 0.0
12, 4.0, 1.0, 0.0 
*NODE
 5, 3.0, 0.0, 0.0
11, 3.0, 1.0, 0.0
*NSET, NSET=NODE2
FRONT_S,
*NSET, NSET=SOLID
FRONT_S,CENTER_S,BACK_S
*NSET,NSET=ACOUS
BACK_F,FRONT_F
*ELEMENT, TYPE=CPS4R, ELSET=SOLID
1, 1, 2, 8, 7
2, 2, 3, 9, 8
*ELEMENT,TYPE=AC2D4R, ELSET=FLUID 
3, 4, 5, 11, 10
4, 5, 6, 12, 11
*ELEMENT, TYPE=ACIN2D2, ELSET=INF
5, 12, 6
*ACOUSTIC WAVE FORMULATION, TYPE=TOTAL
*SOLID SECTION, ELSET=INF, MATERIAL=FLUID
1.0, -100.0, 0.1, 0.0
*SOLID SECTION, ELSET=SOLID, MATERIAL=ELAS
1.0,
*MATERIAL, NAME=ELAS
*ELASTIC
207E9,0.3
*DENSITY
7800.0
*****
*SOLID SECTION, ELSET=FLUID, MATERIAL=FLUID
1.0
*MATERIAL, NAME=FLUID
*ACOUSTIC MEDIUM, BULK MODULUS
2.25E9
*ACOUSTIC MEDIUM, CAVITATION LIMIT
0.0001
*DENSITY
1000.0
**
*SURFACE,NAME=SOLID
2,S2
*SURFACE,NAME=FLUID
3,S4
*TIE,NAME=COUPLE
SOLID,FLUID
**
*BOUNDARY
BACK_S,1,2
**
*AMPLITUDE,NAME=SINE,DEF=PERIODIC
1,<omega>,0.0,0.0
0,1,0,0
**
** Step 1
**
*STEP 
*DYNAMIC,EXPLICIT, IMPROVED DT METHOD=NO
,<T1>
*BOUNDARY, AMP=SINE
 5,8,,1e6
11,8,,1e6
*OUTPUT,FIELD, VARIABLE=PRESELECT
*OUTPUT, HISTORY, VARIABLE=PRESELECT
** Output Request for QA Purposes **
*NSET, NSET=QA_TEST
NODE2
*OUTPUT,FIELD,NUMBER INTERVAL=1
*NODE OUTPUT,NSET=QA_TEST
U,
POR
*OUTPUT,HISTORY,TIME INTERVAL=0.5
*ENERGY OUTPUT,VARIABLE=PRESELECT
*******
*END STEP