Volume 20, Numéro 1, Pages 123-143

Discharge Coefficient Relationship For The Smbf Flume

Authors : Achour Bachir . Amara Lyes .


The discharge coefficient Cd, defined as the ratio of the experimental flow rate to the ideal flow rate, is an important parameter. It is the ultimate correction factor for the theoretical stage-discharge relationship when it is determined on the basis of simplifying assumptions. To understand the behaviour of the flow rate Q, the plot of Q as a function of the stage h is insufficient because the influence parameters are not detected. Plotting the experimental discharge coefficient against the relative upstream flow depth, related to the width of the approach channel, is the best way to know which are the parameters that influence the flow rate and hence the stage-discharge relationship. This can sometimes reveal the existence of unsuspected influential phenomena. Regarding the SMBF flume, the literature does not report any relationship likely to govern the discharge coefficient of the device. Studies have focused on the stage-discharge relationship without alluding to the discharge coefficient. The stage-discharge relationships available in the literature are of two types. There are formulas of complex form, totally locked, which do not allow any possibility of development or expansion to extract the discharge coefficient relationship hidden inside. There are formulas that are rather simple in form but require transformations to highlight the unapparent discharge coefficient relationship. It is the last type of formula that will be addressed in this study. For each stage-discharge relationship proposed by the literature, the main objective is to associate it with the relationship that governs the discharge coefficient and to highlight the influential parameters. The different models describing the discharge coefficient of the device will be compared with the observations available in the literature, and interesting conclusions will be drawn.


SMBF flume ; Flow measurement ; Stage-discharge ; Discharge coefficient