Calculation of fully developed turbulent flow in rectangular ducts with two opposite roughened walls

Abstract

The predictive capabilities of three transport-type turbulence models are analyzed by comparing predictions with experimental data obtained for fully developed turbulent flow in a square duct (Case 1) and in a 2:1 aspect ratio rectangular duct (Case 2), each with two opposite rib-roughened walls. The models include the Demuren-Rodi (DR) k-ϵ model, the Sugiyama et al. (S) k-ϵ model, and the differential stress (DS) model proposed recently by the authors. For Case 1, the S model is unable to predict experimentally observed axial mean velocity distortion induced by secondary flow in the cross plane. For both test cases, the DR and DS models exhibit similar levels of performance, except in the vicinity of a corner formed by the juncture of adjacent smooth and rib-roughened walls, where the DS model outperforms the DR model. The results are analyzed to explain why the DR model leads to the formation of a spurious secondary flow cell near this corner that is not present in the experimental flow.