Turbulence Model Predictions of Extra-Strain Rate Effects in Strongly-Curved Flows

The abilities of three types of turbulence models to accurately predict the effects of curvature on flow in a U-duct are studied. An explicit algebraic stress model performs better than one- or two-equation linear eddy viscosity models, although it is necessary to fully account for the variation of the production-todissipation -rate ratio in the algebraic stress model formulation. None of the turbulence models fully captures the suppressed turbulence near the convex wall or enhanced turbulence near the concave wall. However, a full Reynolds stress model predicts the suppressed turbulence near the convex wall. Some of the underlying assumptions used in the development of algebraic stress models are investigated and compared with the computed flow field from a full Reynolds stress model. Through this analysis, the assumption of Reynolds stress anisotropy equilibrium used in the algebraic stress model formulation is found to be suspect in regions of strong curvature