NUMERICAL AND EXPERIMENTAL INVESTIGATION OF TURBULENT-FLOW IN A RECTANGULAR DUCT

Details of the turbulent flow in a 1:8 aspect ratio rectangular duct a t a Reynolds number of approximately 5800 were investigated both numer ically and experimentally. The three-dimensional mean velocity field a nd the normal stresses were measured at a position 50 hydraulic diamet ers downstream from the inlet using laser doppler velocimetry (LDV). N umerical simulations were carried out for the same flow case assuming fully developed conditions by imposing cyclic boundary conditions in t he main flow direction. The numerical approach was based on the finite volume technique with a non-staggered grid arrangement and the SIMPLE C algorithm. Results have been obtained with a linear and a non-linear (Speziale) k-epsilon model, combined with the Lam-Bremhorst damping f unctions for low Reynolds numbers. The secondary flow patterns, as wel l as the magnitude of the main flow and overall parameters predicted b y the non-linear k-epsilon model, show good agreement with the experim ental results. However, the simulations provide less anisotropy in the normal stresses than the measurements. Also, the magnitudes of the se condary velocities close to the duct corners are underestimated. (C) 1 998 John Wiley & Sons, Ltd.