open TELEMAC-MASCARET The mathematically superior suite of solvers

Dear all,

I would like to assign different friction coefficients in different zones in my mesh, and I do not really understand how to do that. I read the Appendix 6 in the TELEMAC2D user manual. It is said that I must provide a code number for each node of the domain, the nodes sharing the same code number will have the same friction coefficient. This can be done manually thanks to the friction_user.f subroutine. What do you imply by "manually"? I took a look at the subroutine and I do not understand where and what parameters I should include in order to define these zones. And how do I choose the value of the code number?

I saw also that this friction_user.f subroutine can read a file where you have the correspondence between node and code numbers. An example of this file was provided in the Donau validation case. But how do you generate it ? Is it possible to define these zones visually in Blue Kenue, assign their own friction coefficients and then export everything as ascii file to be read later by the friction_user.f subroutine?

Thank you for your help.

Regards,

Jean-Philippe

Hi JP,

For simple variable friction coefficient, I use Bluekenue.

1. Draw a closed polygon around a region of your domain that you want a different friction coeff.

2. When your done, assign as elevation of the polygon the value of friction parameter that you want.

3. Create a geo file. Add variable BOTTOM FRICTION and use BK map object function to attach the polygon to BOTTOM FRICTION mesh.

4. Make sure in your cas file you set a value for friction parameter ... If BOTTOM FRICTION is in your geo.slf, you should get a message in the listing telling that friction is read in geo file. The value in cas file will then be ignored but it has to be there because you'll get error msg if not.


Mathieu

Thanks Mathieu,

I am doing your way now, and it seems to work although I did not run yet a simulation. However, I also have polygons with higher friction coefficients enclosed in other polygons, and when I want to map them on the bottom-friction object, they do not appear on the map.

Any reason why they don't show up ?

Thanks

JP

Sorry, I found the problem. It was just that I was confused by the legend scale. The enclosed polygons were mapped but since the legend scale was not updated, they did not appear on the bottom_friction mesh. Once I reloaded the legend scale, it worked!

Thanks anyway for the suggestion

JP

Hello,

I am not able to answer all your questions (my BAW colleagues will probably explain how they generated the file in the Donau example, anyway I do not like very much this formatted file that raises problems in parallel, with the loop on the original global number of points, it would probably be better it it were a Selafin file that would be split in parallel) but to answer one of your questions the code number is quite arbitrary.

If you have a simple definition of your zones that can be written in Fortran it is not necessary to read a file. If you are able to add your code number as a variable given in the geometry file, like what is done with bathymetry and friction, it should not be too difficult to read it, like what is done in subroutine FONSTR in library bief, with subroutine FIND_IN_SEL, so you can consider these two options.

Regards,

Jean-Michel Hervouet