Analysis of heat transfer performance for turbulent viscoelastic fluid-based nanofluid using field synergy principle

In this paper, the field synergy principle is firstly performed on the viscoelastic fluid-based nanofluid and other relevant fluid in channel at turbulent flow state to scrutinize their heat transfer performance based on our direct numerical simulation data-base. The cosine values of intersection angle between velocity vector and temperature gradient vector are calculated for different simulated cases with varying nanoparticle volume fraction, nanoparticle diameter, Reynolds number and Weissenberg number. It is found that the filed synergy effect is enhanced when the nanoparticle volume fraction is increased, nanoparticle diameter is decreased and Weissenberg number is decreased, i.e. the heat transfer is also enhanced. However, the filed synergy effect is weakened with the increase of Reynolds number which may be the possible reason for the power function relationship in empirical correlation of heat transfer between heat transfer performance and Reynolds number with the constant power ex- ponent lower than 1. Finally, it is also observed that the field synergy principle can be used to analyze the heat transfer process of viscoelastic fluid-based nanofluid at the turbulent flow state even if some negative cosine values of intersection angle exist in the flow field.