Modeling of three-dimensional flow in turning channels

The present finite difference solutions of the time-averaged Navier-Stokes equations in three dimensions, determining the structure of developing flows inside curved channels, are in primitive variables and involve a combination of repeated space-marching integrations of the governing equations and corrections for elliptic effects between two marching sweeps. This procedure allows efficient calculations of turbulent flow to be conducted inside strongly curved channels, as well as of laminar flow inside a moderately curved passage; results obtained for both cases indicate that the flow structure is strongly controlled by local imbalance between centrifugal forces and pressure gradients. The secondary flow's distortion of primary flow is found to be largely dependent on the Reynolds number and the Dean number. Comparisons are made with experimental data.