*HEADING 
EXPONENTIALLY DROPPING PLANE PRESSURE WAVE LOADING ON A MASS-SPRING-MASS 
SYSTEM FLOATING ON A COLUMN OF FLUID THAT CAN CAVITATE.  COMPARE THE ABAQUS
SOLUTION WITH THAT BY SPRAGUE AND GEERS (2001).   
CASE 1: M2/M1=0 
**
FLUID COLUMN DEPTH: 3.0M
ACOUSTIC ELEMENT HEIGHT = 2.5E-3M   I.E 1200 ELEMENTS. 
ACOUSTIC ELEMENT WIDTH = 0.01M 
ACOUSTIC ELEMENT THICKNESS = 1.0M
DRAFT OF THE FLOATING MASSES = 5.08M 
PATM = 0.101E6 PA.
**
*PREPRINT, MODEL=YES, HISTORY=YES
**
*PART,NAME=MODEL
*END PART
**
*ASSEMBLY,NAME=ASSEMBLY
**
*INSTANCE,NAME=INST,PART=MODEL
*NODE
1,    0.0,  0.0
1201,  0.0, -3.0  
2001, 1.E-2,  0.0    
3201, 1.E-2, -3.0
*NGEN, NSET=LEFT
1, 1201 
*NGEN, NSET=RIGHT
2001, 3201 
*NSET, NSET=FLUID
LEFT, RIGHT
*ELEMENT, TYPE=AC2D4R
1, 1, 2, 2002, 2001
*ELGEN, ELSET=FLUID
1,1200  
*SURFACE, NAME=TOP
1, S4 
*SURFACE, NAME=BOT
1200, S2 
*SOLID SECTION, ELSET=FLUID, MATERIAL=FLUID 
1.0
**
*NODE, NSET=MASS
4001, 0.0,   0.0
5001, 1.E-2, 0.0
*NSET, NSET=MASS1
4001, 5001
*ELEMENT, TYPE=MASS, ELSET=MASS
4001, 4001
5001, 5001
*MASS, ELSET=MASS
26.035
*SURFACE, NAME=FLOAT, TYPE=NODE
MASS1
*END INSTANCE
**
*TIE, NAME=MASS2FLUID
INST.TOP, INST.FLOAT
**
*END ASSEMBLY
**
*ACOUSTIC WAVE FORMULATION, TYPE=TOTAL WAVE
*MATERIAL, NAME=FLUID
*ACOUSTIC MEDIUM, BULK MODULUS
2.30625E9,
*ACOUSTIC MEDIUM, CAVITATION LIMIT 
0.0,
*DENSITY
1025.0,
**
*INITIAL CONDITIONS, TYPE=ACOUSTIC STATIC PRESSURE
INST.FLUID,  0.101E6, 0.0, 5.08, 0.0, 0.212412E6, 0.0, -6.0, 0.0
*INCIDENT WAVE PROPERTY,NAME=IWPROP,TYPE=PLANE
0.0, -3.0,
0.0, -4.0,
*INCIDENT WAVE FLUID PROPERTY
2.30625E9, 1025.0
*AMPLITUDE,DEFINITION=TABULAR,NAME=PRESSUREVTIME
 0.000D+00, 0.000D+00, 0.587D-05, 0.203D-02, 0.117D-04, 0.805D-02, 0.176D-04, 0.180D-01
 0.235D-04, 0.318D-01, 0.294D-04, 0.493D-01, 0.352D-04, 0.705D-01, 0.411D-04, 0.953D-01
 0.470D-04, 0.124D+00, 0.529D-04, 0.155D+00, 0.587D-04, 0.191D+00, 0.646D-04, 0.229D+00
 0.705D-04, 0.271D+00, 0.764D-04, 0.316D+00, 0.822D-04, 0.364D+00, 0.881D-04, 0.415D+00
 0.940D-04, 0.469D+00, 0.999D-04, 0.526D+00, 0.106D-03, 0.585D+00, 0.112D-03, 0.648D+00
 0.117D-03, 0.713D+00, 0.123D-03, 0.781D+00, 0.129D-03, 0.851D+00, 0.135D-03, 0.924D+00
 0.141D-03, 0.100D+01, 0.194D-03, 0.882D+00, 0.247D-03, 0.779D+00, 0.300D-03, 0.687D+00
 0.352D-03, 0.607D+00, 0.405D-03, 0.535D+00, 0.458D-03, 0.472D+00, 0.511D-03, 0.417D+00
 0.564D-03, 0.368D+00, 0.617D-03, 0.325D+00, 0.670D-03, 0.287D+00, 0.723D-03, 0.253D+00
 0.775D-03, 0.223D+00, 0.828D-03, 0.197D+00, 0.881D-03, 0.174D+00, 0.934D-03, 0.153D+00
 0.987D-03, 0.135D+00, 0.104D-02, 0.119D+00, 0.109D-02, 0.105D+00, 0.115D-02, 0.930D-01
 0.120D-02, 0.821D-01, 0.125D-02, 0.724D-01, 0.130D-02, 0.639D-01, 0.136D-02, 0.564D-01
 0.141D-02, 0.498D-01, 0.146D-02, 0.439D-01, 0.152D-02, 0.388D-01, 0.157D-02, 0.342D-01
 0.162D-02, 0.302D-01, 0.167D-02, 0.266D-01, 0.173D-02, 0.235D-01, 0.178D-02, 0.208D-01
 0.183D-02, 0.183D-01, 0.189D-02, 0.162D-01, 0.194D-02, 0.143D-01, 0.199D-02, 0.126D-01
 0.204D-02, 0.111D-01, 0.210D-02, 0.980D-02, 0.215D-02, 0.865D-02, 0.220D-02, 0.764D-02
 0.226D-02, 0.674D-02, 0.231D-02, 0.595D-02, 0.236D-02, 0.525D-02, 0.241D-02, 0.463D-02
 0.247D-02, 0.409D-02, 0.252D-02, 0.361D-02, 0.257D-02, 0.318D-02, 0.263D-02, 0.281D-02
 0.268D-02, 0.248D-02, 0.273D-02, 0.219D-02, 0.278D-02, 0.193D-02, 0.284D-02, 0.170D-02
 0.289D-02, 0.150D-02, 0.294D-02, 0.133D-02, 0.300D-02, 0.117D-02, 0.305D-02, 0.103D-02
 0.310D-02, 0.912D-03, 0.315D-02, 0.805D-03, 0.321D-02, 0.710D-03, 0.326D-02, 0.627D-03
 0.331D-02, 0.553D-03, 0.337D-02, 0.488D-03, 0.342D-02, 0.431D-03, 0.347D-02, 0.380D-03
 0.352D-02, 0.335D-03, 0.358D-02, 0.296D-03, 0.363D-02, 0.261D-03, 0.368D-02, 0.231D-03
 0.374D-02, 0.203D-03, 0.379D-02, 0.180D-03, 0.384D-02, 0.158D-03, 0.390D-02, 0.140D-03
 0.395D-02, 0.123D-03, 0.400D-02, 0.109D-03, 0.405D-02, 0.961D-04, 0.411D-02, 0.848D-04
 0.416D-02, 0.749D-04, 0.421D-02, 0.661D-04, 0.427D-02, 0.583D-04, 0.432D-02, 0.514D-04
 0.437D-02, 0.454D-04, 0.442D-02, 0.401D-04, 0.448D-02, 0.354D-04, 0.453D-02, 0.312D-04
 0.458D-02, 0.275D-04, 0.464D-02, 0.243D-04, 0.469D-02, 0.214D-04, 0.474D-02, 0.189D-04
 0.479D-02, 0.167D-04, 0.485D-02, 0.147D-04, 0.490D-02, 0.130D-04, 0.495D-02, 0.115D-04
**
*BOUNDARY
INST.MASS, 1,1, 0.0
INST.MASS, 3,6, 0.0
*STEP
*DYNAMIC, EXPLICIT, DIRECT USER CONTROL
8.333E-7,170.0E-3
*BULK VISCOSITY
0.5,
*SIMPEDANCE
INST.BOT,
*INCIDENT WAVE,PRESSUREAMPLITUDE=PRESSUREVTIME,PROPERTY=IWPROP
INST.BOT,16.15E6 
*OUTPUT, FIELD, NUMBER INTER=100
*NODE OUTPUT, NSET=INST.LEFT
POR, PABS 
*OUTPUT, HISTORY, TIME INTERVAL=1.7E-4
*NODE OUTPUT, NSET=INST.MASS
U2,V2,A2
*END STEP