Performance of RNG turbulence modelling for forced convective heat transfer in ducts

This investigation concerns numerical calculation of turbulent forced conve ctive heat transfer and fluid flow in straight ducts using the RNG (Re-Norm alized Group) turbulence method. A computational method has been developed to predict the turbulent Reynolds stresses and turbulent heat fluxes in ducts with different turbulence mode ls. The turbulent Reynolds stresses and other turbulent flow quantities are predicted with the RNG k-epsilon model and the RNG non-linear k-epsilon mo del of Speziale. The turbulent heat fluxes are modeled by the simple eddy d iffusivity (SED) concept, GGDH and WET methods. Two wall functions are used , one for the velocity field and one for the temperature field. All the mod els are implemented for an arbitrary three dimensional duct. Fully developed condition is achieved by imposing cyclic boundary condition s in the main flow direction. The numerical approach is based on the finite volume technique with a non-staggered grid arrangement. The pressure-veloc ity coupling is handled by using the SIMPLEC-algorithm, The convective term s are treated by the QUICK scheme while the diffusive terms are handled by the central-difference scheme. The hybrid scheme is used for solving the k and epsilon equations. The overall comparison between the models is presented in terms of friction factor and Nusselt number. The secondary flow generation is also of major concern.