A numerical approach for the heat fluxes analysis in the nearwall region

A difficult task in the analysis of the heat transfer by convection is to define the heat flux trend in the fluid layer close to the surface. When the problem is treated using Computation Fluid Dynamics (CFD) it is important to adopt an appropriate mesh resolution in the boundary layer. This process can take long calculation times and the obtained results are not always correct. The boundary layer can be modelled with two numerical methods: the wall functions, which link the outermost zone of the boundary layer to the wall, or the near-wall model. The choice of the most suitable method is related not only to an accurate geometrical discretization of the near-wall domain, but also to another parameter: the dimensionless wall distance (y+). For this reason a parametric study of the most commonly adopted families of wall functions and near-wall models has been carried out in terms of accuracy of the results vs. computational costs. The aim of this work is to define an efficient methodology for the heat flux in the near-wall region in order to find the optimal approach according to the needs of the analysis.