open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi

I'm starting with the calibration of a large model of the Scheldt estuary. I have data from different water level measurement stations along this estuary. To calibrate and adjust water levels in the estuary I use the friction coëfficiënt.
I understood that in order to assign different friction coefficients to different parts of the estuary I have to use a subroutine and program this in fortran.

I wondered if there was an easier way to do this.

I was thinking of assigning the friction coefficients to parts of the estuary in ArcGIS software; create a xyz file with as z values the friction coefficients and write a subroutine to read this data into telemac. This method could allow me to easely change friction coefficients in ArcGIS.

Has anyone experience in doing this?

regards,

Sven

Hi sven

It's easy to manage friction coefficient in the fudaa interface.
You can define manually some polygons (or import them from ArcGis) and give the value of the friction coefficient.
In this case, the friction coefficient is define as an initial condition.
The Fudaa Training of the next week users club will show how to manage the spatial variation of the friction coefficient (it's one of the most important point for hydrodynamic simulation)

Christophe

Hi Sven,

Another possibility is that there is in telemac-2d a procedure done for zonation of friction coefficient, initially developed at BAW. An example is in the telemac-2D test case called Donau. I enclose a provisonial version of telemac-2d user manual that is nearly ready to be published, where this is described.

Regards,

Jean-Michel

Hi Sven,

It is possible to save your roughness directly in the geometry file and it will be read by T2D at runtime. In this way you can avoid programming roughness assignment in a fortran subroutine. You can use polygons in Blue Kenue or Fudaa-prepro to do so.

Personally, I define my zones using more or less complex polygons in BlueKenue. I assign roughness values to each polygon and map it on the mesh which I then save as an slf. Your geometry file will then contain two data layers (FOND and FROTTEMENT in the french version). I do a test run in T2D and update the roughness value as necessary until I get expected results.

If drawing polygons becomes tedious (irregular channels), I work with an xyz roughness map and assign individual values to nodes using an AWK routine (any language will do). I then triangulate this data set in BlueKenue and map it to the mesh. Export this in the geometry slf and I'm ready to go.

See attached figure for an example of irregular roughness zone definition in Blue Kenue. The main channel roughness is in blue.

cheers

jeremie

Forgot to attach the roughness figure.

Jeremie,

thanks. Your solution can save me a lot of time.

Do you create the polygons in Blue Kenue via closed lines or do you import them? Do you use the map object function with the mesh as destination and the closed line as a source? I don't seem to get an extra datalayer in my mesh.

Sven

Hi Sven,

first you have to save your mesh as another mesh file.
You can create closed lines in BlueKenue and assign them a value (in this case a roughness value) or import closed shapelines from GIS or also from text files following the Blue Kenue file structure. When mapping with the option "Map Object" the roughness mesh file is the destination data item and the closed line the source data.
The attribute name in your mesh file should be "BOTTOM FRICTION".
After that, you drag both the elevation mesh file and the roughness mesh file to the selafin object.

Regards,
Clemens

Hi Sven,

I do exactly as Clemens explained. Either open two copies of the mesh file or copy it using the calculator in BlueKenue. Rename de roughness layer as BOTTOM FRICTION or FROTTEMENT if you use the French version.

The first thing I do is set the BOTTOM FRICTION layer to a constant roughness coeff. by mapping a polygon that surrounds the whole mesh. I then add smaller polygons (or import closed polylines from *.mif files for example) to which different roughness are associated and map those as well.

Once everything is ok, i drag and drop BOTTOM and BOTTOM FRICTION on a new selafin object and I'm done.

regards

j

Hi all,

I tried to do everything as mentioned before. I created the blue kenue selafin file (big endian) with BOTTOM and BOTTOM FRICTION in it.
Then Icreated a new telemac file. I have as friction coef a Manning Coefficient. I I marked the key word 'friction data' and assigned the selafin file as friction data file.
When I try to run the simulation it stops immediately and gives an error: read error zone
What is missing here? What am I doing wrong?

regards

Sven

Hi Sven

The keywords "friction data" exist in telemac in order to define an ascii file (where you describe some zone) for an automatic application of friction coefficient.
In you rcase, the friction coefficient is given in the selafin file. So you just have to run a simulation with the selafin file as a previous compuation file and Telemac will read the friction in the previous file.

Regards