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Hello,

I'm currently trying to model a flood on a 14 km reach and I need to calibrate my model. I tried to search for the keyword for Discharge in GRAPHIC PRINTOUTS but I didn't find it.

Is there a way to print the discharge and not the scalar one ?


Thank you :)

Hello Barbara,

If I understood well, you want to get the flowrate as vectors along your domain.

In that case, try with:
I: Flowrate along X axis (m2/s).
J: Flowrate along Y axis (m2/s).

I hope this helps.

Cheers,
José Andrés.

Thank you for your answer !
Actually is it possible to get the discharge in m3/s ?

Hello,

In that case you should printout "Q" which is the Scalar Flowrate (per unit of width) expressed in m2/s and integrate it along a section.

In BK:
1. Create a line.
2. Select the line - tools - integrate along line - scalar flowrate - ok.

I think that should work.

I hope this helps.

Cheers,
José Andrés.

Dear Jose and Barbara,

Integrating scalar flow following that procedure won't take into account the direction of the flow regarding the cross section orientation, leading to unexpected results in a fair chunk of cases.

Just to name a trivial one, drawing a parallel line to the flow direction in a river/channel and integrating directly scalar flow "Q" results in a discharge really different to 0 (or something really really close to it).

The appropriate methodology using bluekenue would be to print I and J (components of the scalar flow field) and integrate along a line, as mentioned in this discussion.

On the other hand, I believe PostTelemac (Artelia's plugin for QGis) has a tool to calculate discharge over time in a defined section, really useful if you are dealing with a unsteady state model.

Regards,

José Díaz.

Hello

Another hint is to use control section during telemac run. please see the user manual to know how to make it work.


with my kind regards

Riadh

Hi riadh

I caught the attention of your comment, and I generate a doubt.

From what I understand, it should indicate the start and end node, but my doubt is how telemac calculates the flow ?, Integrates the flow at all nodes between the initial and final node? Or generates a line between the initial and final node and integrates with respect to any node that is near that line? I do not know if you understand the difference of what I'm asking you?

regards

Joaquin

Thank you for all your answers !

Hello Joaquin,

Actually, both options you've mentioned should give the same result. The discharge computation consists on the integration of the velocity vector dot the normal unitary vector multiplied by the water depth. This integration is achived on the segment between starting and ending points. If you use any path between both points you should obtain the same results.

Telemac looks for mesh nodes between starting and ending points and achieves the integration.
You can have a look on subroutines flusec_telemac2d.f or flusec_t2d.f to see 2 ways to integrate the discharge through control sections.

with my kind regards

Riadh