Computational analyses of heat flux of wall Y⁺ in supercritical fluid using star – Ccm+ Cfd code

Abstract

Theoretical modeling techniques on resolving turbulent heat flows in a nondimensionalcircular tube mounted obstacle using the wall Y+ as guidance in selecting the appropriate grid configuration and corresponding turbulence models are investigated using CFD Code. The results obtained shows that the heat fluxes of 20, 23, 30 and 40 kW/m², increases as the Y⁺wall profile moves away from the near – wall region, this is due to the effect of viscosity, buoyance, acceleration and the friction of the turbulence modification.The results also indicates that the low Y⁺wall treatment is suitable only for low Reynolds turbulence models in which it is assumed that the viscous sub-layer is  properly resolved. The simulated results obtained in this research are in good agreements with the experimental results in the literature,
even though they over predicted the observed heat transfer deterioration both quantitatively and qualitatively.

Keywords: Wall Y⁺ , Turbulence, Supercritical fluid, Heat flux