adiabatic walls yet enthalpy change

Chris

Hi,

I've got flow through a pipe with a throat and adiabatic walls. The temperatures at inlet and outlet are equal, at 300K.

Presumably, under adiabatic conditions, with no work done on the flow within the pipe, I would not expect any change in the stagnation enthalpy of the fluid, right?

Yet, downstream of the throat, I get regions of higher stagnation temperature (~330K), which are then convected down the pipe.

Fluent reports that this is the converged solution, but I don't see how it makes sense!

Thanks in advance, if you are able to provide some valuable insight!

Chris