[majkl]

Originally Posted by cosimobianchini

I'm not familiar with starCCM+, is it solving energy equation in terms of thermal (static) or total enthalpy. There is a sensible difference in case of high acceleration due to the different discretization of the source terms including viscous heating.

Well, it is physically correct to solve the full energy equation (here without action of body forces, e.g. gravity):
kinetic energy + enthalpy (e+p/rho) = "heat flux term" + "viscous term" ( (partial/partial x)(friction stress tensor*velocity) ).