Author(s): M. F. Maghrebi; M. Givehchi
Linked Author(s):
Keywords: No Keywords
Abstract: A number of equations have been proposed to determine the dispersion coefficients analytically since 1950. However, it is realized that it is difficult to use these equations for predicting the dispersion coefficients, because the detailed information on velocity profile and cross sectional geometry are required to calculate them. To solve the problem, researchers tried to introduce the empirical equations. In this paper it is attempted to get back to the fundamental analytical equations, because it is believed that a simple model which is proposed by Maghrebi, can provide a good prediction of normalized isovel contours in the cross section of open or closed irregular channels both in roughness and in geometry. The input data for the model are the bed profile and its shear and roughness distributions. Having obtained the isovel contours, the depth-averaged velocity profile at a cross section can be extracted. In order to extract the parameters that characterize the longitudinal dispersion coefficients, application of the model to the cross sections of the Sacramento Delta, Northern California, is presented. The results of this study show that the longitudinal dispersion coefficient obtained by the use of isovel contours is close to the coefficients produced by the measured as well as other methods.
Year: 2009