problem with temperature modeling in a reservoir - Forum - Delft3D-Old

Hello everybody,

I set up a very simple model of a reservoir. I am modeling a stationary scenario using two boundary conditions which are based on measurements:
-upstream: discharge (inflow)
- downstream: (outflow) the corresponding water level (see Fig. 1 for the location of the open boundaries and the flow direction).
When I run Delft3d-Flow for this simple case, the results are just as expected (regarding water level in the model area and flow direction).
The problem appears, when I include temperature in the model. In the GUI, I have to introduce the temperature at the two open boundaries. I understand that I need the temperature for the upstream open boundary, since this is the temperature of the incoming water. I thought that for the outflow, I could put any value for the temperature and the model would calculate the correct one (normally we do not have the temperature at the outflow). But this temperature reversed back on the model area. I tried this for different temperatures at the outflow, for all the temperature reversed back!.
For an inflow temperature of 15°C, initial temperature of the water of 20°C and air temperature of 18°C, I obtained the results shown in the Fig 2. (longitudinal profile of the reservoir, when using a temperature of 0°C a the downstream boundary), Fig 3 (velocity vectors for the longitudinal profil) and Fig 4 (velocity vectors for the water surface) . More Info: I am using the heat flux model 1.
Do you have any idea of what I am doing wrong? Do I have to know the temperature at the outflow in order to model the temperature in the reservoir?

Thank you very much in advance for your comments.

Regards,
Johana