Turbulent boundary layers in low Reynolds number shallow open channel flows

The results of an experimental investigation of turbulent nt boundary layers in shallow open channel flows at low Reynolds numbers are presented. The study was aimed at extending the database toward lower values of Reynolds number. The data presented are primarily concerned with the longitudinal mean velocity, turbulent-velocity fluctuations, boundary layer shape parameter and skin friction coefficient for Reynolds numbers based on the momentum thickness (Re-theta) ranging from 180 to 480. In this range, the results of the present investigation in shallow open channel flows indicate a lack of dependence of the von Karman constant kappa on Reynolds number. The extent to which the mean velocity data overlaps with the log-law decreases with decreasing Re-theta. The variation of the strength of the wake with Re-theta is different from the trend proposed earlier by Coles.