Convective discretization schemes for the turbulence transport equations in flow predictions through sharp u‐bends Available to Purchase

This paper presents finite volume computations of turbulent flow through a square cross‐sectioned U‐bend of curvature strong enough(Rc/D =0.65) to cause separation. A zonal turbulence modelling approach is adopted, in which the high‐Re k‐εmodel is used over most of the flow domain with the low‐Re,I‐equation model of k‐transport employed within the near‐wall regions. Computations with grids of different sizes and also with different discretization schemes, demonstrate that for this flow the solution of the k and ε equations is more sensitive to the scheme employed in their convective discretization than the solution of the mean flow equations. To avoid the use of extremely fine 3‐Dimensional grids, bounded high order schemes need to be used in the discretization of the turbulence transport equations. The predictions, while encouraging,displayed some deficiencies in the downstream region due to deficiencies in the turbulence model. Evidently, further refinements in the turbulence model are necessary. Initial computations of flow and heat transfer through a rotating U‐bend, indicate that at rotational numbers (Ro =ΩD/W_b) relevant to blade cooling passages, the Coriolis force can substantially modify the hydrodynamic and thermal behaviour.