VELOCITY DISTRIBUTION IN COMPOUND CHANNEL FLOWS BY NUMERICAL MODELING

The paper examines the problem of prediction of uniform turbulent flow in a compound channel with the nonlinear k-epsilon model. This model is capable of predicting the secondary currents, caused by the anisotropy of normal turbulent stresses, that are important features of the flow in compound channels, as they determine the transverse momentum transfer. The model is applied to reproduce experimental runs available in the literature. The comparison shows that the model predicts with accuracy the distribution of the primary velocity component, the secondary circulation, and the discharge distribution. The numerical results are used to search a subdivision surface between main channel and floodplain on the basis of the flow field and to compare different subdivision surfaces on the basis of the discharge distribution by a simple uniform flow formula. The better subdivision surfaces as predicted by the model are the diagonal surface going from the corner between main channel and floodplain to the free surface on the symmetry plane and the bisector of the same corner.