Comparison of direct numerical simulations and particle-image velocimetry data of turbulent channel flow rotating about the streamwise axis

The influence of rotation about the streamwise axis on a turbulent channel flow is discussed by analyzing and comparing numerical and experimental data. The numerical study uses direct numerical simulations (DNS), while the experiments were based on particle-image velocimetry (PIV). The flow properties in the numerical and experimental analyses were maintained as similar as possible. For comparability with data from the literature the nonrotating channel flow at a Reynolds number Re-tau=180 serves as a reference problem. Depending on the rotation rate of the channel the development of a secondary flow perpendicular to the main flow has been found in both investigations. The rotation primarily influences those components of the Reynolds shear stresses, which contain the spanwise velocity component. The size of the correlation areas and thus the length scales of the flow increase in all three coordinate directions, leading to longer structures. The increased momentum exchange can be deducted from the behavior of the mean main velocity profile, which shows a decreased centerline velocity and an increased velocity near the wall at growing rotation rates. The qualitative development of the mean flow and the statistical flow properties is similar for the simulation and the experiment. The growth of the coherent turbulent structures with the rotation rate is confirmed by both investigations. (C) 2007 American Institute of Physics.