The Boundary Layer Characteristics of Different Turbulence Models in Predicting Supercritical Heat Transfer Behaviors

Abstract

The heat transfer behavior of supercritical water has large difference with that of subcritical water due to its unusual fluid property variation in the pseudo critical region. Computational Fluid Dynamics techniques are playing more and more important roles in investigating the hidden mechanisms of that, however, whether the extension of subcritical turbulence models to supercritical conditions has not yet been fully resolved, especially in heat transfer deterioration situation. The boundary layer is the main region responsible for the heat and momentum transport between the wall and the bulk fluid part, so it is very important for the turbulence models to describe the boundary layer characteristics. In this paper, the two main wall treatment methods- the wall function method and the low Reynolds number model were discussed based on the property variation wall function. It was found that the different turbulent models predicted different boundary layer characteristics which led to the big divergence in predicting the wall temperature. This work was a preliminary step towards the improvement of turbulence models under supercritical conditions.