Turbulent Forced Convection in Ducts

The need for a reliable and reasonably accurate turbulence model without specific convergence problems for calculating duct flows in industrial applications has become more evident. In this chapter a general computational method is presented for calculating turbulent quantities in any arbitrary three-dimensional duct. Four different turbulence models for predicting the turbulent Reynolds stresses, namely the standard k- model, the non-linear k- model of Speziale, an Explicit Algebraic Stress Model (EASM) and a full Reynolds Stress Model (RSM) are compared with each other. The turbulent heat fluxes are modeled by the SED concept, the GGDH and the WET methods. The two-equation model of temperature invariance and its dissipation rate for calculating turbulent heat fluxes is also discussed. The numerical method is based on the finite volume technique with non-staggered grid arrangement. The SIMPLEC algorithm is used for pressure~ velocity coupling. A modified SIP solving method is implemented for solving the equations. The van Leer, QUICK and hybrid schemes are applied for treating the convective terms. Periodic boundary conditions are imposed in the main flow direction for decreasing the number of grid points in this direction. In practical applications, periodic conditions in the main flow direction are commonly justified because in wavy or corrugated ducts such conditions occur naturally.
Keyword: Turbulent, Heat Transfer, Convection, Turbulence Modelling