To analyze flows in channel expansions and contractions, two-dimensional,
depth-averaged, unsteady flow equations are solved by using the two-step Taylor-Galerkin
scheme. The 2-D, depth-averaged equations are written in a fully conservative form. The
solution algorithm is based on an explicit time integration procedure which exploits the
conservative properties of the governing equations. The unsteady flow model is used to
obtain steady flow equations by treating the time variable as an iteration parameter and letting
the solution converge to the steady state. The results of the mathematical model are compared
with experimental data and other models. The capability of the model for handling mixed
super- and sub-critical flows in a channel transition is demonstrated.