Turbulent boundary layers in low Reynolds number shallow open channel flows

The results of an experimental investigation of turbulent nt boundary layer s in shallow open channel flows at low Reynolds numbers are presented. The study was aimed at extending the database toward lower values of Reynolds n umber. The data presented are primarily concerned with the longitudinal mea n velocity, turbulent-velocity fluctuations, boundary layer shape parameter and skin friction coefficient for Reynolds numbers based on the momentum t hickness (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 de creasing Re-theta. The variation of the strength of the wake with Re-theta is different from the trend proposed earlier by Coles.