CFD Validation Of Heat Transfer Correlations With Different Heat Transfer Models

The present work addresses a new effort to improve the prediction of turbulent heat flux in vertical annular and rod bundle geometries by applying the four parameter k-w-kt-et model. These numerical cases are investigated by using an in-house finite element code with a simple implementation of the four parameter model. The k-w turbulence model is employed for simulating the turbulent flow field right up to the wall with no wall functions since the wall functions are available only for ordinary fluids and are not appropriate for low-Prandtl liquid metals. The thermal eddy heat diffusivity can be expressed in a definite manner similar to the viscous eddy diffusivity as a function of the square temperature fluctuation kt and its dissipation rate et. These variables can be computed by solving two new transport equations. Results obtained from the four parameter k-w-kt-et model are compared with the standard turbulent heat flux approximation, namely, the simple eddy diffusivity model.