الفهرس 
Introduction
Scope and objectivesOnly 14 pages are availabe for public view
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Abstract
The development of bounded flows with streamwise curvature in curved ducts and diffusers are distinguished by the generation of streamwise vorticity or ’secondary motion’. The imbalance between radial pressure gradient and centrifugal forces imposed by circular motion forms the secondary motion. The positive streamwise pressure gradient close to the convex surface and the negative streamwise pressure gradient near the concave surface causing a radial pressure gradient. This leads to fluid acceleration closer to the convex surface and deceleration closer to the concave surface. In the present study; computations of two- and three-dimensional turbulent curved flows through two types of square sectioned U-bend duct flows (with mild and strong curvatures) and through 180curved diffuser have been carried out using five turbulence models, provided in the FLUENT code. The numerical results were compared with the existing experimental results. No separation occurs in the mild curvature U-bend, whilst in the strong curvature case, and 180curved diffuser a separating flow appears along the convex wall. The conventional turbulence models, which have been derived based on near homogeneity of the flow, could not predict the flow very well, due to the complex flow phenomenon in the U-bend and curved diffuser. However, the use of advanced turbulence model such as the Reynolds-Stress Model and RNG k-_ model have had more reliable numerical results especially at the separation zone, although the computations take longer time. The reattachment lengths predicted by all models are over-predicted. The comparison between the numerical and experimental results indicated that all models give more reliable results in the three-dimensional analysis in comparison with two-dimensional.