Abstract
The nonlinear effects on water released waves (WRWs) in channels with significantly varying cross-sections, under subcritical flow, is examined.
To describe the nonlinear effects, first the new concept of the average celerity of a kinematic wave, C, based on the quasi-uniform flow approach, is introduced, and then the relationship of discharge and average celerity of kinematic wave (Q-C curve) is obtained. Using the Q-C curve, a hypothesis is set up in which the difference of average celerity of kinematic waves between two steady flows, κ(=ΔC), represents a constant characterizing the tendency of nonlinear effects of the convective term on WRWs. This hypothesis agrees with the results of unsteady flow simulations.
It is found that the average celerity of a kinematic wave is smaller in a nonprismatic channel than in a prismatic channel, and that, in the case of an increase in discharge, nonlinear effects become smaller and even negative nonlinear effects can arise.
