II.   Construction of the mesh with Matisse.

The first step consisted in creating the bathymetry of the problem. We made a file telling Matisse the position of the the points we felt were the most important. There are positionned at the edges of each side of the valley. We first thought it was not necessary to put some points in the middle of the rivers but the tests we have made showed that the flow went out of the modelised zone. So, we had to increase the number of points describing the bathymetry. Here is the bathy.sx we have used : (the last column deals with the height of the point.)

C       Fichier /tmp_mnt/nfs/lhf_a/users3/telcom/INVARIANTS/FORMATION_1997/SINUSX_V2P2/formation.sx
C       Version 2.0 - Date Fri Mar 14 08:56:49 1997
B N +0.000000E+00 +0.000000E+00 +0.000000E+00 +3.000000E+02 +3.000000E+02 +1.000000E+00 1
CP 0 1
CP +2.600000E+02
CP 0
C contour
-0.500000E+03 +0.000000E+00 +0.500000E+00
+0.000000E+00 +0.000000E+00 +0.000000E+00
+0.500000E+03 +0.000000E+00 +0.500000E+00
+0.500000E+03 +5.000000E+03 +5.500000E+00
+8.370000E+03 +1.837000E+04 +2.050000E+01
+6.630000E+03 +1.937000E+04 +2.050000E+01
+0.000000E+00 +6.950000E+03 +5.500000E+00
-1.413000E+04 +3.237000E+04 +3.550000E+01
-1.587000E+04 +3.137000E+04 +3.550000E+01
-0.500000E+03 +5.000000E+03 +5.500000E+00
+0.000000E+00 +5.870000E+03 +4.500000E+00
+7.500000E+03 +1.887000E+04 +1.950000E+01
-1.500000E+04 +3.187000E+04 +3.450000E+01

    Then, we used Matisse to generate the mesh. The geometry we have visualised was :


We enlarged the bottom of the modelised area to avoid the problem of a too important confluence of the floods. The result on the bathymetry (visualised with Rubens) is quite good :

This picture shows that to be at the same level for the side of the valley requires to be further in the denivellation.
Then, we generated the mesh with Matisse. The mesh is composed of about 3500 nodes. We decided to place nodes along the deepest points of the aera to modelise the phenomenon very precisely.
Here is the mesh we obtained for the top of the aera :

And for the bottom of the aera :


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