open TELEMAC-MASCARET The mathematically superior suite of solvers

Please help, I am new in Telemac, I am building a model for the Western Scheldt estuary (in The Netherlands) using a simplified approach (Idealized model), and forcing the model with just an M2 tidal component. I am a bit sstuck in prescribing tidal constituent M2 at my offshore boundary.

I would like to realize 3 things:

1) Initially, i want to prescribe an M2 components at the offshore boundary that varies only in time (without using any tidal data base). I know i can specfify the M4 tidal elevation (SL) in the liquid boundary file, with a certain amplitude+phase. But i was wondering if there is an option in Telemac (like in the model Delft3D) where u can specify just the amplitude and phase as input parameters, instead of generating a timeseries of an M2 component in the liquid boundary file. I have been reading already 2 days through the forum to discover how to do such a thing but i got quite confused how to do that. I would think that such a thing would be very simple: amplitude+phase of M2 and that's it, or, maybe i missing something!

2) Similar to case 1), but now I want to prescribe at the offshore boudnary an M4 component that varies both in space and time. Specifically, i want to impose at each node of my offshore boundary a certain amplitude+phase of M2.
I i understood the topics in the forum correctly, i have to adjust the Bord.f subroutine. I am not a hero in programming, so i was wondering if somebody has an example file bord.f where the amplitude+phase of a tidal constitent (M2 in this case) can be imposed at each boundary node. So, once again please i do'nt want to use any tidal data base, i want to generate everthing myself

3) I am wondering if there is an option to define Neumann boundary conditions (like in Delft3D), or is this the same as Thomson boundary conditions!


I would be very gratefull if somebody would help me on this. Thank you very much.

Kind regards,


Dr. Ab Nnafie
Researcher coastal dynamics
Flemish Government
Department Mobility and Public Works
Flanders Hydraulics Research
Berchemlei 115 - 2140 Antwerp - Belgium
T. +32 (0)486 94 18 47 - F. +32 3 224 60 36

Unfortunately nobody responded. I would appreciate it very much if someone reply to at least one of the questions i raised last time!
Looking forward to hearing from you soon,

Thank u very much.

Dr. Ab Nnafie

Hello,

Yes, in your case the simplest thing to do would be implementing directly subroutine bord.f. This subroutine looks rather complicated because it deals with many possible cases, but its only action is to fill the prescribed values of depth and velocities at the open boundaries, which are called HBOR, UBOR and VBOR. You can look at the example called m2wave in the portfolio of examples and you will find a very simplified version version of subroutine bord.f, probably not far from what you want to do. You can inspire from this example for other issues. In this case both elevation and velocities are prescribed, otherwise you would have to resort to the Thompson's boundary conditions.

The Neumann boundary conditions are for us meant for solid boundary conditions, and give the equivalent of a flux of a quantity across a boundary.

With best regards,

Jean-Michel Hervouet

Dear Mr. Hervouet,

Thank you very much for you suggestions. I will have a look at it.

Kind regards,

Dr. Ab Nnafie