[SarahLee]

Dear all,

I am testing the BC externalWallHeatFluxTemperature on a simple case: room with window in contact with outdoor air. These are my boundary conditions:
- exterior air temperature Ta: -4 °C = 269.15 K
- exterior heat transfer coefficient h = 25 W/(m²K)
- glass between exterior and interior domain: R = 1.73 m2K/W, d = 0.02 m, lambda = 0.012 W/(mK)
- interior temperature appr. 20 °C

I implement this as follows:

glass
  {
     type            externalWallHeatFluxTemperature;
     kappa           lookup;
     Ta              uniform 269.15;                    //external air temperature K
     h               uniform 25;                             //external heat transfer coefficient (W/m²K)
     thicknessLayers (0.020);                      //thickness glass (m)
     kappaLayers     (0.012);                         //equivalent heat conductivity glazing W/(mK)
     kappaName       alphaEff;
     value           uniform 273.15;
  }

Is this correct?
In the resulting interior flow field, the air temperature just adjacent to this wall is -4 °C. This doesn't make sense to me, as this value should be implemented outside the interior flow domain?

Some feedback is appreciated!

Sarah

[SarahLee]

Dear foamers,

In an attempt to better understand this boundary condition, I did a quick and dirty parameter variation on a simple block. I varied the following parameters:
- h = 1 or 10 W/m²K
- thicknessLayers = 0.2 or 20 m
- kappaLayers = 1 or 5 W/mK
and plotted the results after 1000 iterations. They look basically nearly identical. I have attached a pdf with some screenshots.

Why doesn't it seem to matter what is between my exterior temperature of 300 K and my internal field?

Thanks!

Sarah

[wc3speler]

Hi!

Did you find out why the temperature in the internalField near the wall turns out to be what you specified for the outside domain?