Turbulence characteristics of two-dimensional channel flow with system rotation

Turbulence quantities have been measured for a low-Reynolds-number fully developed two-dimensional channel flow subjected to system rotation. Turbulence intensities, Reynolds shear stress, correlation coefficient, skewness and flatness factors, four-quadrant analysis, autocorrelation coefficient and power spectra are investigated. According to the dimensional analysis, the relevant parameters of this flow are the Reynolds number Re* = u*D/v and the Coriolis parameter Rc = Omega v/u*(2) for the wall region, and Re* and Omega D/u* for the turbulent core-region. The existence of a Coriolis region where turbulence intensities are defined by a new variable y(c)(*) = y/delta(c), has been clarified on the pressure side in the rotating channel flow. The amount of turbulent kinetic energy transported by the Coriolis term is extremely small compared to the production term in the transport equation of Reynolds normal stress. However, the Coriolis term makes a large contribution to Reynolds shear stress transport on the pressure side of the channel. It is caused by the strong ejection which occurs periodically on the pressure side even though the ejection frequency is low. The strong ejection is conjectured to be caused by a large-scale longitudinal structure like a roll cell on the pressure side of the channel.