open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi,

As decribed in the manual, Telemac 2D offers two possibilities regarding flow computation through structures : weirs and culvert. It is thus not possible to define a structure that could have both behaviour, for example a bridge at low and high flows.

Is there a trick to do it ? Or may there be a chance that such a discharge law function can be added on the next releases ?

Thank you in advance,
PL

Hi

This is a tentative answer and I hope that it will be completed/modified by other users and colleagues.

I've never tried such case, but I don't see why one can not combine a weir and a culvert at the same location. If you look at the user manual, the weir is defined with two sets of boundary nodes which should correspond 1 to 1. The flowrate is then obtained using some ampiric formulae depending on the case "submerged" or "unsubmerged" weir.

set 1 + + + +
set 2 + + + +

For the culvert, you have to link two points which are declared as source points and which are identified with their coordinates
ABSCISSAE OF SOURCES: X1 ; X2
ORDINATES OF SOURCES: Y1 ; Y2
WATER DISCHARGE OF SOURCES: 0. ; 0.
So for the example I give here, you can define 4 culverts.

In such way, the culverts will be actived for all free surface and weir will be activated only when the threshold is reached.

Some questions have to be clarified. I guess that the computed flowrate for weir will be dependant on the one of the culverts; so one can ask if the hydraulic laws used for both structures will stay valid. Moreover, the calibration of the obtained model is easy or not?
I'm curious to see if the solution is working or not, is efficient or not.

to be continued ...

Riadh

Hi !

Thank for your reply.
I thought about this possibility, but it does not function for the case I am thinking about :
- structure functions as a weirs for low flow (bridge when Zwater < Ztop culvert)
- structure functions as a culvert for high flows (bridge when Zwater > Ztop culvert
This is then valid only if you don't have overtopping on the bridge deck.

Your suggestion is interesting is the functionment is the opposite, which is the case of small bridges.

Regards,
PL

Hi

I will discuss about your suggestion with the Telemac developer team and we will see if we can move forward into your idea.
We welcome also any contribution from Telemac users and/or from forum visitors.

Kind regards.
Riadh

Hi

It's not to difficult to program such things starting from the culvert program and adding the weir equation when the water level is under the top level of culvert.
I've done such developement long time ago but we never validate it for all case.
Eventually, we could envisage to inplement it in the next version. We will discuss about this point at the next scientific development meeting.

regards

Hi CHristophe,

Thanks for your reply. Yes, i guess it is not something hard to program, but i am not skillful in that ! (especially with fortran).
I think it would be a great function to implement in the next releases since this problem can be faced very often in river engineering modeling cases.

Regards,
Pierre-Louis