Reasons for Unexpected Reported Heat Flux at the Inlets

The Reported Total Heat Flux at inlets is not as expected, what can be the reason?

The heat flux with which a mass flow enters a domain (or leaves it) can be computed as:

mdot*cP*(Tin – Tref)

where Tref is fixed in the code to 298.15K

Comparing this with the heat flux computed using the total heat transfer rate from the flux reports there can be a large difference between these values.

One possible reason could be radiation. If a radiation model is activated, the inside of the domain exchanges energy by radiation with the outside. The total heat flux is the sum of all heat flows across the boundary. It can be checked by also reporting the radiation heat flux and computing the difference. This should give the value computed by the equation above.