Capability of non liner eddy viscosity model in predicting complex flows

Abstract

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.

The research field of the study is related with turbulence modeling. The general objective is the implementation in a commercial code, of two equations Non Linear Eddy Viscosity Model (NLEVM) which removes Boussinesq linear approximation for the Reynolds stress tensor. The work described in the paper implements a second order k-ε model based over Shih, Zhu and Lumley (1993) [1] and Craft, Launder and Suga (1996) [2] in the finite volume commercial code ANSYS-FLUENT v. 6.3.26, by writing additional subroutines. The model has been validated through experimental and DNS data available in the literature. The benchmarks shown in this paper are the straight Square Duct [8] and the Backward-Facing Step [9, 10]. After the validation, the model has been used for predicting the flow behavior for complex industrial applications. The geometry used is similar to the bowl-shape downcomer of nuclear reactor. This is an application field of interest still under study by the same research group and an international consortium.