Simulation Accuracies of Gradually Varied Flow

Two types of errors which occur in the numerical simulation of gradually varied, unsteady open-channel flows are investigated in this paper: (1) errors resulting from the choice of the momentum equation; and (2) errors resulting from the degree of numerical sophistication of integration techniques used in solving the governing equations by the specified intervals scheme of the method of characteristics. It was found that three different momentum equations cited in the literature give identical results when the velocity distribution is uniform. When this distribution is not uniform, each equation gives somewhat different flow depths for similar initial and boundary conditions of gradually varied, unsteady flow. An increase in complexity of the integration technique increases the accuracy of simulation. To determine the absolute values of accuracy of a technique, the development of accurate flow measuring devices and corresponding experiments are needed for comparison between the results of numerical and physical simulations.