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Abnormally high values of Oxygen and NO3 in simulation coupled with Telemac

SN
Sathya narayanan, modified 4 Years ago.

Abnormally high values of Oxygen and NO3 in simulation coupled with Telemac

Youngling Posts: 3 Join Date: 3/13/14 Recent Posts
Hi,

I am running a water quality simulation coupled with Telemac.
The effluent has an ambient condition of dissolved oxygen of 7 g/m3 and discharge concentrations of 1 g/m3.
Similarly for NO3 it is ambient 0.3 g/m3 and discharge concentration of 29.79 g/m3.

When I run the simulation with discharge quantity of for example a low quantity of 205 m3/s, the minimum and maximum values of pollutants
in the domain varies within the range of ambient and effluent concentration. (i.e for oxygen 0 - 7 g/m3, and for NO3 0.3 to 29.79 g/m3)

However when I run the simulation with very high effluent quantity of 1083000 m3/s, the value range abnormally high
of the range 2e10+3 for oxygen and 3e10+3 for NO3.

Is there any parameter which I should use to limit the values of the modeled pollutants.
I have given a time step of 5 seconds with a FEM mesh of minimum 10 m element side size.

Thanks,
Sathyanaryanan
Michel Jeuken, modified 4 Years ago.

RE: Abnormally high values of Oxygen and NO3 in simulation coupled with Tel (Answer)

Jedi Knight Posts: 156 Join Date: 1/21/13 Recent Posts
Hi Sathyanaryanan,

Did you change the discharge in the hydro dynamical model accordingly?

Although it is possible in DELWAQ to change the flow discharge for a waste load, this doesn't affect the hydrodynamics. This can lead to an accumulation of substances in the receiving location since the amount of water flowing from this segment will not change.

And do you really model a discharge of 1083000 m3/s? It is quite a lot I would say...

Michel
SN
Sathya narayanan, modified 4 Years ago.

RE: Abnormally high values of Oxygen and NO3 in simulation coupled with Tel

Youngling Posts: 3 Join Date: 3/13/14 Recent Posts
Hi Michel,

Sorry for my late reply, and also thank you very much for the quick reply.
Yes the discharge quantity was too much for the simulation as you have mentioned.

The discharge is over a range of time, apparently I had given it at every second, for the range of time.
I have changed it appropriately and now it is working properly.

With Best Regards,
Sathyanaryanan