*HEADING
1D TRANSIENT WAVE PROPAGATION IN AN ACOUSTIC MEDIUM WITH CLOAD 
IN ABAQUS/EXPLICIT [AC2D4R]; 
VERIFICATION PROBLEM: TRANSIENT DYNAMICS TESTS
**
** C=SQRT(K/RHO)= 343.05 M/S   K=BULK MODULUS, 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
** FOR EXAMPLE AT THE END OF THE SIMULATION : 
**                   P_1(0,0.0044)=1.826
**                   P_51(0.5,0.0044)=1.221
**                   P_101(1.0,0.0044)=0.616
** THE ACCELERATION IS SPECIFIED USING *CLOAD ON DOF 8
**
** SEE CH. 3.7.7 OF ABAQUS/VERIFICATION MANUAL
**
*PREPRINT,ECHO=NO,HISTORY=NO,MODEL=YES
*NODE,NSET=NALL
    1, 0,
  101, 1,
 1001, 0, 1.e-2
 1101, 1, 1.e-2
*NGEN,NSET=NALL
    1,101
 1001,1101
*NSET,NSET=LOAD
 1,1001
**
*NSET,NSET=QA_TEST,GEN
1,10,1
45,55,1
90,101,1
*NSET,NSET=NOUT
QA_TEST,
*ELEMENT,TYPE=AC2D4R 
 1,1,2,1002,1001
*ELGEN,ELSET=CHANNEL
 1,100
*SOLID SECTION,MATERIAL=AIR,ELSET=CHANNEL
 1e-2, 
** CROSS-SECTION IS 1e-4  
**
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
**
**
*RESTART,WRITE, NUMBER=1
**
*STEP
*DYNAMIC,EXPLICIT
,.0044
** DEFINE NONREFLECTIVE BOUNDARY AT X=1
*IMPEDANCE
100,I2
**
** PRESCRIBE VOLUME ACCELERATION INWARDS
**     DISTRIBUTE HALF TO EACH NODE ON EDGE.
**
*CLOAD
LOAD,8,0.5e-4
*************************
*OUTPUT,FIELD,NUMBER INTERVAL=1
*NODE OUTPUT
POR
*************************
*OUTPUT,HISTORY, TIME INTERVAL=0.00022
*NODE OUTPUT, NSET=NOUT
POR
*************************
*END STEP