open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

I am simulating a coupled t2d-sisyphe model for bed evolution in a real river. The steering file for t2d and sisyphe are attached.

I am using non-uniform sediment where I set the sum of the fraction equal to one. Simulation is running fine. But at the 39th day as shown in the attached error photo, in the sediment slide part error occurs which say (in layer 1 sum of fractions, not 1, stop after an error in layer).

The total sum of each sediment fraction is one as I supplied in the steering file. Is this error related to the layer of active thickness? or something else.

Any suggestion on how can I rectify this problem?

Thank you.

Saroj

Hi Saroj,


It looks like a rounding error in the sediment slide calcultations. If you are not too worried about the mass conservation (the errors are fairly small), you can add the layer.f subroutine to your fortran files and remove the stop/arret commands that are triggered by the fraction checks:

IF(TEST1.GT.ZERO.AND.(TEST1-1.D0)**2>ZERO) THEN
! WRITE(LU,*) ' PROBLEM IN LAYER: J,TEST1',J,TEST1
! WRITE(LU,*) ' IN LAYER 1 SUM OF FRACTIONS NOT 1'
! ARRET=1
ENDIF

Michiel

Dear Michiel,

Thank you.

Is it Ok if I remove the stop/arret commands for both the layers like shown below?

IF(TEST1.GT.ZERO.AND.(TEST1-1.D0)**2>ZERO) THEN
! WRITE(LU,*) ' PROBLEM IN LAYER: J,TEST1',J,TEST1
!WRITE(LU,*) ' IN LAYER 1 SUM OF FRACTIONS NOT 1'
!ARRET=1
ENDIF
IF(TEST2.GT.ZERO.AND.(TEST2-1.D0)**2>ZERO) THEN
!WRITE(LU,*) ' PROBLEM IN LAYER: J,TEST2',J,TEST2
!WRITE(LU,*) ' IN LAYER 2 SUM OF FRACTIONS IS NOT 1'
!ARRET=1
ENDIF

So it will not affect other aspects of sisyphe simulation?

Regards,
Saroj

Hi Saroj,

of course, the round of error does effect the results from then on, but in my experience this corrects itself over time and does not get worse. Other than a small error in the sediment mass conservation, there is no significant impact I am aware off. I end up removing the stop commands almost all the time for long-term simulations.

Dear Michiel,

The error on the 'sum of sediment fractions' was removed after commenting on the commands as you suggested.

But I encountered another error as attached below. I checked the subroutine layer.f, the error comes the following lines of the command,

DO I=1,NSICLA
DO K=1,NLAYER%I(J)
! CHECKS THAT AVAIL IS IN THE RANGE (-ZERO,1+ZERO)
IF(AVAIL(J,K,I).GT.1.D0+ZERO.OR.AVAIL(J,K,I).LT.-ZERO) THEN
WRITE(LU,*) 'ERROR ON FRACTIONS'
WRITE(LU,*) 'LAYER ',K,' CLASS ',I,' POINT ',J
IF(AVAIL(J,K,I).LT.0.D0) THEN
WRITE(LU,*) 'AVAIL=' ,AVAIL(J,K,I)
ELSE
WRITE(LU,*) 'AVAIL-1=' ,AVAIL(J,K,I)-1.D0
ENDIF
WRITE(LU,*) 'ZFCL=',ZFCL_W%ADR(I)%P%R(J)
WRITE(LU,*) 'EVOL=',EVOL,' ELAY=',ELAY%R(J)
ARRET=1
ELSE
! ONCE CHECKED THAT WE HAVE ONLY TRUNCATION ERRORS, CLIPS
AVAIL(J,1,I)=MAX(AVAIL(J,1,I),0.D0)
AVAIL(J,1,I)=MIN(AVAIL(J,1,I),1.D0)
ENDIF
ENDDO
TEST1 = TEST1 + AVAIL(J,1,I)
TEST2 = TEST2 + AVAIL(J,2,I)
ENDDO

I increased the 'ELAY0 = 10000.D0 * ACLADM%R(J)'. However, the error was the same.

Is it the problem with the timestep (dt) or something else?

Is it OK if we comment the lines above?

Thank you.

Saroj

Saroj

you will need to comment out a few more stop/arret statements in layer.f (there are quite a few of them).