The heat flux on internals / interiors is not computed during the run and you are therefore not able to post process it directly. However, as a workaround you can use a Named Expression like: Sum(SpecificEnthalpy,[‘interface’],Weight =’MassFlowRate’). Be aware this expression is an approximation that does not include radiative and diffusive terms, but only the convective part. Also, this expression is only an approximation which shows limitations in accuracy for flow that is tangential to the internal but is quite accurate if you have a flow normal to the internal. As a result, you should place internals in a way that the main flow path is normal to them if possible. Keywords: Fluent; heat flux; internal; internals; interior; interiors; zone; zones; surface; surfaces; convection; convective; flux; process; post-process