Abstract
Correlation between the oblique upward flow and coherent structure formed over flood plain in compound open channel flows was investigated by using flow visualization techniques. The results of velocity measurements using PTV show that the oblique upward flow and a pair of cellular secondary current are generated over the edge of the flood plain. This flow filed is characterised by two velocity shear structures (∂U/∂U, ∂U/∂z). Further, it becomes clear that longitudinal vortical structures exist over the edge of the flood plain for a long period. The vortical structure directly contributes to form instantaneous oblique upward flow and cellular secondary current.
