First things first, the inlet temperatures do not appear to be the same. The scale on the lower plot shows it might be 1K whereas above it is 20C.

Why, in the lower image, why is there a big change in the T? I am not sure what the colored non-blue structure is in the lower section. We don’t know the problem as well as you, so I would recommend showing the same image when comparing things.

You, also, mentioned this is a transient simulation. Is this the first time step or later on in the simulation?

What is the expected pressure drop through the U shape domain? And what will happen to the density and temperature as the pressure changes (ideal gas case)?