RESULTS




        This part of the study is dedicated to the use of TELEMAC on the mesh built with MATISSE. All graphs are generated by the software RUBENS. This study is composed of two parts: a simple case and a flood case.

1.A simple case:

    In this case, the two flows are the same and constant, Q1=Q2=10m3/s and the water height at the end of the river is imposed at 0.2m. Initially, the water height is uniform and its value is 0.1m. The nest pictures show the water height evolution in time. Simmulations have been made with a 20 seconds timestep during three hours:

           We can see fere that the water height after 200 seconds stay at about 0.1m everywhere in the river. Only a little quantity of water has mooved toward the middle of the river where it is supposed to go because it is the deepest zone. The simmulation needs more time to arrive to the established state where the water height is important in the center and about zero near sides.

        After about 17min, much more water has mooved toward the center of the river. In fact the water height in the bed of the river is about 0.2m-0.25m.

    After one hour, the water height near the sides is about zero, therefore the establshed state is not far but not already obtained. Moreover the water has also moved throw
the river. We can see that the water height is quite importante in the confluence zone (about 0.45m).

            After three hours, the water seems to be well established: the water height is nul near sides, about 0.3m in the middle (it has not mooved much since the one hour test) and the confluence zone becomes bigger and bigger. We can supposed that the established state has been obtained.
 

2.The flood case:

   With Telemac, it is possible to create function to use them inside the main program. That what we have done, to generate a flow such as Q=f(t). To do that we had this small program at the end of the file princi.f:

     IMPLICIT NONE
      INTEGER LNG,LU
      COMMON/INFO/LNG,LU
      INTEGER I,NPOIN
      DOUBLE PRECISION T , DEBIT(*) , H(NPOIN)
      INTRINSIC MIN

C DEBIT A LA SORTIE

       if (I.eq.1) then
       DEBIT(I) = 400 * H(66) * H(66) *sqrt (H(66))

C DEBIT A L'ENTREE 1 (PIC A 1000)

        elseif (I.eq.2) then
        if (T.LE.3600) then
        DEBIT(I) = 10.
        elseif ( (T.GT.3600).AND.(T.LE.21600) ) then
        DEBIT(I) = 0.055 * (T-3600) + 10.
        elseif ( (T.GT.21600).AND.(T.LE.57600) ) then
        DEBIT(I) = - 0.0275 * (T-21600) + 1000.
        elseif  (T.GT.57600) then
        DEBIT(I) = 10.
        endif

C DEBIT A L'ENTREE 2 (PIC A 2500)

        elseif (I.eq.3) then
        if (T.LE.3600) then
        DEBIT(I) = 10.
        elseif ( (T.GT.3600).AND.(T.LE.21600) ) then
        DEBIT(I) = 0.138333 * (T-3600) + 10.
        elseif ( (T.GT.21600).AND.(T.LE.57600) ) then
        DEBIT(I) = - 0.0691665 * (T-21600) + 2500.
        elseif  (T.GT.57600) then
        DEBIT(I) = 10.
        endif
        endif

        Q = DEBIT(I)
        RETURN
        END
 

   In this way, the flow boundary conditions follow exactly the evolution given by the graph in the part Presentation of the case, in order to simulate a real flood.

    The following pictures represent the evolution with time of the flood case. The simulations have been made with a 1 minute time step during 17 hours:




             We can see in this test that in the three first pictures, we find exactly the previous test without flood and its evolution to an established state. This step is necessary during all test. Then we can the apparition of the flood like we have generated it and with a water height about 2m in the left river and about 1m in the right one. The flood evoluate in the river to the confluence. In the confluence zone, effects of flood in the two rivers are added to join a water hight upper 3m.
    Those results seems to be coorect because the flood and its evolution is well simulate by the software.
 
 

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