XY plots big difference node and face values (thermal boundary layer)
 

Hi,

I am simulating the cooling process due to natural convection in a tank.
I am using stand wall functions and k-epsilon model (tank height is 20 m)

The question is that when I plot the temperature profile next to the walls to see the thermal boundary layer, there is a difference on about 0.5ºC (Tin - Tout = 1.8 for face values and 2.3 for node values). I want to calculate the heat transfer coeffcient, but the difference is big due to this. I do not know what I should use, node values or face values. The gradient option in the solver is face based.

The shape also change a little bit between the two options.

Thanks in advance