Modelling of heat transfer in computational fluid dynamics

The scope of this thesis is to introduce advanced modelling of heat flux in turbulent flows into CFD. Explicit algebraic scalar flux modelling (EASFM) is considered and previous models are simplified in order to avoid near-wall damping functions and wall distance dependencies. The modification was verified by computations of fully developed channel flow with heat transfer. One of the original goals, to implement a EASFM into the research code of FOI (EDGE), could not be reached and the reason for this was related to numerical stability. The attempted implementation was analyzed, and a method to overcome the problems was proposed. The capability of the EDGE CFD code concerning numerical accuracy in the prediction of heat transfer using more standard heat flux models was assessed for fully developed turbulent channel flow. The code was found o be rather inaccurate for the combination of isothermal walls and low Mach number with regard to prediction of skin friction and wall heat flux. A comparison of several turbulence models as well as the two CFD solvers EDGE and Fluent was carried out using a plane impinging jet case with DNS data used for reference. Known model differences was confirmed and the low Mach number sensitivity of EDGE was also obvious here while Fluent better agreed with DNS data.