PHOTON USE
  p
 
 
 
  msg       ******************************************************
  msg       *  Note:                                             *
  msg       *               ========                             *
  msg       *  Inspect the result file of d_priv1 to see the     *
  msg       *  numerical data.                                   *
  msg       ******************************************************
  MSG Press E to end
  ENDUSE
     GROUP 1. Run title and other preliminaries
TEXT(ABSORPTIVE DISPERSAL WITH TIME DEPENDENT SOURCE:111

  DISPLAY 
    Zero-dimensional diffusion problem which can be tested  against
    exact solution. 
  =================================================================
     Unsteady dispersal problem:
       dF/dt=exp(t)-5F
     Initial conditions:
        t=0, F=1
     Exact solution:
        F=1./6.(exp(t)+5.exp(-5t))
  ==================================================================
  One computational cell is used in this study of the
  time variation of pollutant concentration.
  ENDDIS

    GROUP 2. Transience; time-step specification
STEADY=F;GRDPWR(T,12,1.0,1.0)
    GROUP 7. Variables stored, solved & named
SOLVE(C1)
    GROUP 8. Terms (in differential equations) & devices
TERMS(C1,N,N,N,Y,Y,N)
    GROUP 11. Initialization of variable or porosity fields
FIINIT(C1)=1.0
    GROUP 13. Boundary conditions and special sources

   PLANTBEGIN
PATCH(SOURCE,CELL,1,NX,1,NY,1,1,1,lstep)
    VAL=EXP(TIM)/5.
COVAL(SOURCE,C1,5.,GRND)
      * Exact solution for output
STORE(EXCT)
   EXCT=1./6*(EXP(TIM)+5.*EXP(-5.*TIM))
   PLANTEND  
 
    GROUP 15. Termination of sweeps
LSWEEP=2
NAMSAT=MOSG
SPEDAT(SET,GXMONI,TRANSIENT,L,F)
    GROUP 21. Print-out of variables
    GROUP 23. Field print-out and plot control
IPROF=2
PATCH(TIMEPLOT,PROFIL,NX,NX,1,1,NZ,NZ,1,LSTEP)
PLOT(TIMEPLOT,C1,0.0,1.0);PLOT(TIMEPLOT,EXCT,0.0,1.0)
tstswp=-1
dmpstk=t
DISTIL=T
EX(C1)=4.689E-01; EX(EXCT)=4.587E-01
 LIBREF=111
STOP