Comparison of linear and nonlinear RNG-based k-ε models for incompressible turbulent flows

摘要

Linear and nonlinear renormalization group (RNG) k-ε models are compared for the prediction of incompressible turbulent flows. The multidimensional finite-volume code KIVA-3 is used to explore the alternative models versus the standard k-ε model. Test cases include the classic backward-facing step and the confined co-flow jet flows. Our results suggest that the linear RNG k-ε model can yield significant improvements over the standard k-ε model for recirculatory flows, because of its less dissipative nature. While the nonlinear RNG k-ε model can also improve predictions compared to the standard k-ε model, its greatly increased cost compared to the linear RNG model renders it less attractive. However, for the case of shear flows, such as for confined co-flow jets, the RNG-based k-ε models are in less favorable agreement with experiments compared to the standard k-ε model. Overall, it is concluded that combining the claimed universality of the RNG-based k-ε model constants with the anisotropies introduced by the nonlinear k-ε model cannot enhance predictions of both recirculating and shear incompressible flows.